Producing composite nanoparticles

ABSTRACT

A method for producing a composite nanoparticle, including the steps of: changing the conformation of a dissolved polyelectrolyte polymer from a first extended conformation to a more compact conformation by changing a solution condition so that at least a portion of the polyelectrolyte polymer is associated with a precursor moiety to form a composite precursor moiety with a mean diameter in the range between about 1 nm and about 100 nm; and cross-linking the polyelectrolyte polymer of the composite precursor moiety to form a composite nanoparticle.

This application claims the priority of U.S. Provisional ApplicationNos. 60/726,184 filed Oct. 14, 2005, U.S. patent application Ser. Nos.11/745,377, and 11/749,507, both filed May 16, 2007 and PCT ApplicationNo. PCT/CA06/001686, filed Oct. 13, 2006, the entire contents of all ofwhich are incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to methods for producing composite nanoparticlescomprising nanoparticles confined within cross-linked collapsedpolymers, and nanoparticles per se; said composite nanoparticles,nanoparticles and carbon-coated nanoparticles.

BACKGROUND OF THE INVENTION

Nanoparticles are nanometer-sized materials e.g., metals,semiconductors, polymers, and the like, possessing uniquecharacteristics because of their small size. Nanoparticles in bothaqueous and non-aqueous solvents can be synthesized using a variety ofmethods.

The conformation of a polymer in solution is dictated by variousconditions of the solution, including its interaction with the solvent,its concentration, and the concentration of other species that may bepresent. The polymer can undergo conformational changes depending on thepH, ionic strength, cross-linking agents, temperature and concentration.For polyelectrolytes, at high charge density, e.g., when “monomer” unitsof the polymer are fully charged, an extended conformation is adopteddue to electrostatic repulsion between similarly charged monomer units.Decreasing the charge density of the polymer, either through addition ofsalts or a change of pH, can result in a transition of extended polymerchains to a more tightly-packed globular i.e. collapsed conformation.The collapse transition is driven by attractive interactions between thepolymer segments that override the electrostatic repulsion forces atsufficiently small charge densities. A similar transition can be inducedby changing the solvent environment of the polymer. This collapsedpolymer is itself of nanoscale dimensions and is, itself, ananoparticle. In this specification and claims the term “collapsedpolymer” refers to an approximately globular form, generally as aspheroid, but also as an elongate or multi-lobed conformation collapsedpolymer having nanometer dimensions. This collapsed conformation can berendered irreversible by the formation of intramolecular chemical bondsbetween segments of the collapsed polymer, i.e. by cross-linking.

Macromolecules, i.e. polymers with the appropriate functional groups canundergo inter- or intra-molecular cross-linking reactions to produce newmaterials or new molecules with distinct properties, such as forexample, shape, solubility, thermal stability, and density. Thesereactions are important in making new materials and various schemes forchemical reactions leading to cross-linking are described in theliterature. For example, U.S. Pat. No. 5,783,626—Taylor et al, issuedJul. 21, 1998, describes a chemical method to cross-linkallyl-functional polymers in the form of latexes, containing enaminemoieties and pendant methacrylate groups via a free-radicalcross-linking reaction during film formation producing coatings withsuperior solvent resistance and increased thermal stability. Polymercross-linking has also been used to stabilize semiconductor and metalnanoparticles. U.S. Pat. No. 6,872,450—Liu et al, issued Mar. 29, 2005,teaches a method for stabilizing surface-coated semiconductornanoparticles by self assembling diblock polymers on the surface coatingand cross-linking the functional groups on the diblock polymer.Similarly, U.S. Pat. No. 6,649,138—Adams et al, issued Nov. 18, 2003,describes how branched amphipathic dispersants coated onto hydrophobicnanoparticles can also be cross-linked to form a permanent cohesive overcoating around the nanoparticle.

Chemical means of cross-linking can be through radical reactions ofpendant groups containing unsaturated bonds as described in aforesaidU.S. Pat. No. 5,783,626. Another method is through the use of moleculeshaving multifunctional groups than can react with the functional groupsof the polymer as described in aforesaid United States U.S. Pat. No.6,649,138 and U.S. Pat. No. 6,872,450. Alternatively, cross-linking canbe achieved though high energy radiation, such as gamma radiation. Themost common method of preparing chalcogenide semiconductor nanocrystalsis the TOP/TOPO synthesis (C. B. Murray, D. J. Norris, and M. G.Bawendi, “Synthesis and Characterization of Nearly Monodisperse CdE(E=S, Se, Te) Semiconductor Nanocrystallites,” J. Am. Chem. Soc.,115:8706-8715, 1993). However, this method again involves multiplechemical steps and large volumes of expensive and toxic organometallicmetal precursors and organic solvents. Furthermore, such nanoparticlesneed to be chemically modified in order to render them soluble inaqueous solution, which is important for a number of applications.Chalcogenide nanoparticles have also been synthesized in aqueoussolution at low temperature using water-soluble thiols as stabilizingagents ((a) Rajh, O. L. Mićić, and A. J. Nozik, “Synthesis andCharacterization of Surface-Modified Colloidal CdTe Quantum Dots,”J.Phys.Chem., 97: 11999-12003, 1993. (b) A. L. Rogach, L. Ktsikas, A.Kornowski, D. Su, A. Eychmüller, and H. Weller, “Synthesis andCharacterization of Thiol-Stabilized CdTe Nanocrystals,” Ber. Bunsenges.Phys. Chem., 100(11):1772-1778, 1996. (c) A. Rogach, S. Kershaw, M.Burt, M. Harrison, A. Kornowski, A. Eychmüller, and H. Weller,“Colloidally Prepared HgTe Nanocrystals with Strong Room-TemperatureInfrared Luminescence,” Adv. Mater. 11:552-555, 1999. (d) Gaponik, N.,D. V. Talapin, A. L. Rogach, K. Hoppe, E. V. Shevchencko, A. Kornowski,A. Eychmüller, H. Weller, “Thiol-capping of CdTe nanocrystals: analternative to organometallic synthetic routes,” Journal of PhysicalChemistry B, 2002, vol. 106, iss. 39, p. 7177-7185. (e) A. L. Rogach, A.Kornowski, M. Gao, A. Eychmüller, and H. Weller, “Synthesis andCharacterization of a Size Series of Extremely Small Thiol-StabilizedCdSe Nanocrystals,” J. Phys. Chem. B. 103:3065-3069, 1999). However,this method generally requires the use of an inert atmosphere withmultiple processing steps and production of precursor gases. Anotherwater-based synthesis involves the formation of undesirable by-productsthat must first be removed before semiconductor particles can beobtained (H. Zhnag, Z. Hou, B. Yang, and M. Gao, “The Influence ofCarboxyl Groups on the Photoluminescence of MercaptocarboxylicAcid-Stabilized Nanoparticles,” J. Phys. Chem. B, 107:8-13, 2003).

CdTe nanocrystals are known to have tunable luminescence from green tored and have shown tremendous potential in light-emitting thin films (A.A. Mamedov, A. Belov, M. Giersig, N. N. Mamedova, and N. A. Kotov,“Nanorainbows: Graded Semiconductor Films from Quantum Dots,” J Am.Chem. Soc., 123: 7738-7739, 2001), photonic crystals (A. Rogach, A.Susha, F. Caruso, G. Sukhoukov, A. Kornowski, S. Kershaw, H. Möhwald, A.Eychmüller, and H. Weller, “Nano- and Microengineering:Three-Dimensional Colloidal Photonic Crystals Prepared fromSubmicrometer-Sized Polystyrene Latex Spheres Pre-Coated withLuminescent Polyelectrolyte/Nanocrystal Shells,” Adv. Mater. 12:333-337,2000), and biological applications (N. N. Memedova and N. A. Kotov,“Albumin-CdTe Nanoparticle Bioconjugates: Preparation, Structure, andInterunit Energy Transfer with Antenna Effect,” Nano Lett.,1(6):281-286, 2001). PbTe and HgTe materials exhibit tunable emission inthe infrared and look promising in the telecommunications industry. HgTenanoparticles have been incorporated into more sophisticated assemblies,particularly as components in thin-film electroluminescent devices ((a)A. L. Rogach, D. S. Koktysh, M. Harrison, and N. A. Kotov,“Layer-by-Layer Assembled Films of HgTe Nanocrystals with StrongInfrared Emission,” Chem. Mater., 12:1526-1528, 2000. (b) É. O'Conno, A.O'Riordan, H. Doyle, S. Moynihan, a. Cuddihy, and G. Redmond,“Near-Infrared Electroluminescent Devices Based on Colloidal HgTeQuantum Dot Arrays,” Appl. Phys. Lett., 86: 201114-1-20114-3, 2005. (c)M. V. Kovalenko, E. Kaufmann, D. Pachinger, J. Roither, M. Huber, J.Stang, G. Hesser, F. Schäffler, and W. Heiss, “Colloidal HgTeNanocrystals with Widely Tunable Narrow Band Gap Energies: FromTelecommunications to Molecular Vibrations,” J. Am. Chem. Soc.,128:3516-3517, 2006) or solar cells (S. Günes, H. Neugebauer, N. S.Sariiciftci, J. Roither, M. Kovalenko, G. Pillwein, and W. Heiss,“Hybrid Solar Cells Using HgTe Nanocrystals and Nanoporous TiO₂Electrodes,” Adv. Funct. Mater. 16:1095-1099, 2006). PbTe, on the otherhand, can be grown in a variety of glasses at high temperatures toproduce composite materials for applications in optoelectronic devices((a) A. F. Craievich, O. L. Alves, and L. C. Barbosa, “Formation andGrowth of Semiconductor PbTe Nanocrystals in a Borosilicate GlassMatrix,” J. Appl. Cryst., 30:623-627, 1997. (b) V. C. S. Reynoso, A. M.de Paula, R. F. Cuevas, J. A. Medeiros Neto, O. L. Alves, C. L. Cesar,and L. C. Barbosa, “PbTe Quantum Dot Doped Glasses with Absorption Edgein the 1.5 μm Wavelength Region,” Electron. Lett., 31(12):1013-1015,1995).

Doping of CdTe with Hg results in the formation of CdHgTe compositenanocrystals. Red shifts in absorbance/photoluminescence spectra andenhanced PL are observed with increasing Hg content (A. L. Rogach, M. T.Harrison, S. V. Kershaw, A. Kornowski, M. G. Burt, A. Eychmüller, and H.Weller, “Colloidally Prepared CdHgTe and HgTe Quantum Dots with StrongNear-Infrared Luminescence,” phys. scat. sol., 224(1):153-158, 2001).Cd_(1-X)Hg_(X)Te alloys are popular components in devices used fornear-IR detector technology. A variety of methods have been developed tocreate these materials. U.S. Pat. No. 7,026,228—Hails et al, issued Apr.11, 2006, describes an approach to fabricating devices and semiconductorlayers of HgCdTe in a metal organic vapour phase epitaxy (MOVPE) processwith mercury vapor and volatile organotelluride and organocadmiumcompounds. In a different approach, U.S. Pat. No. 7,060,243—Bawendi etal, issued Jun. 13, 2006, describes the synthesis oftellurium-containing nanocrystals (CdTe, ZnTe, MgTe, HgTe and theiralloys) by the injection of organometallic precursor materials intoorganic solvents (TOP/TOPO) at high temperatures. U.S. Pat. No.6,126,740—Schulz, issued Oct. 3, 2000, discloses another non-aqueousmethod of preparing mixed-semiconductor nanoparticles from the reactionbetween a metal salt and chalcogenide salt in an organic solvent in thepresence of a volatile capping agent.

Mixtures of CdTe and PbTe have also been investigated for IR detectionin the spectral range of 3 to 5 μm. However, because these materialshave such fundamentally different structures and properties (S. Movchan,F. Sizov, V. Tetyorkin. “Photosensitive Heterostructures CdTe—PbTePrepared by Hot-Wall Technique,” Semiconductor Physics, QuantumElectronics & Optoelectronics. 2:84-87, 1999. V), the preparation of thealloy is extremely difficult. U.S. Pat. No. 5,448,098—Shinohara et al,issued Sep. 5, 1995, describes a superconductive device based onphoto-conductive ternary semiconductors such as PbCdTe or PbSnTe. Dopingof telluride quantum dots, e.g. CdTe, with transition metals, e.g. Mnoffers the possibility of combining optical and magnetic properties inone single nanoparticle ((a) S. Mackowski, T. Gurung, H. E. Jackson, L.M. Smith, G. Karczewski, and J. Kossut, “Exciton-ControlledMagnetization in Single Magnetic Quantum Dots,” Appl. Phys. Lett. 87:072502-1-072502-3, 2005. (b) T. Kümmel, G. Bacher, M. K. Welsch, D.Eisert, A. Forchel, B. König, Ch. Becker, W. Ossau, and G. Landwehr,“Semimagnetic (Cd,Mn)Te Single Quantum Dots—Technological Access andOptical Spectroscopy,” J. Cryst. Growth, 214/215:150-153, 2000).Unfortunately, these materials are mostly fabricated using thin-filmtechnologies such as molecular beam epitaxy or chemical vapourdeposition and the necessity for a very controlled environment duringgrowth makes these materials inaccessible. Some mixed-metal telluridessuch as CdHgTe (S. V. Kershaw, M. Burt, M. Harrison, A. Rogach, H.Weller, and A. Eychmüller, “Colloidal CdTe/HgTe Quantum Dots with HighPhotoluminescence quantum Efficiency at Room Temperature,” Appl. Phys.Lett., 75: 1694-1696, 1999); and CdMnTe (N. Y. Morgan, S. English, W.Chen, V. Chernornordik, A. Russ, P. D. Smith, A. Gandjbakhche, “RealTime In Vivo Non-Invasive Optical Imaging Using Near-InfraredFluorescent Quantum Dots,” Acad. Radiol, 12(3): 313-323, 2005) quantumdots have been prepared in aqueous solution which is an adaptation ofthe synthetic technique outlined in supra Rajh, O. L. et al. However,all of the aforementioned methods involve many processing steps,sophisticated equipment or large volumes of expensive and toxicorganometallic metal precursors and organic solvents.

A simple tellurite reduction method to prepare cadmium telluridematerials has been used using sodium tellurite (Na₂TEO₃) as a telluriumprecursor salt with a suitable reducing agent, such as NaBH₄ with M^(y+)cations (H. Bao, E. Wang, and S. Dong, “One-Pot Synthesis of CdTeNanocrytals and Shape Control of Luminescent CdTe-CystineNanocomposites,” small, 2(4):476-480, 2006).

Accordingly, there is a need in the art for an environmentally friendly,“one-pot”, cost-effective, and generalizable method of directlyproducing metallic, metallic alloyed, semiconductor, oxide, and otherforms of nanocomposite particles having effective functionality in amultitude of scientific disciplines.

SUMMARY OF THE INVENTION

In various aspects, the present invention provides methods of producinga composite nanoparticle comprising a nanoparticle confined within across-linked collapsed polymeric material, which is itself ananoparticle.

The term “composite nanoparticle” in this specification, means ananoparticle substantially confined within a cross-linked, polymericmaterial.

In various aspects, the present invention provides said compositenanoparticles when made by the methods of the present inventions.

In various aspects, the present invention provides methods for providingnon-encapsulated nanoparticles from the aforesaid compositenanoparticles.

In various aspects, the present invention provides methods for producingwholly or partially carbon-coated nanoparticles from said compositenanoparticles.

In various embodiments, the present inventions teaches the ability tomake a wider variety of composite nanoparticles, including oxide,semiconductor, and more complex composite nanoparticles.

In various aspects, the present inventions provide methods for producinga composite nanoparticle comprising the steps of:

a) providing a polymeric solution comprising a polymeric material and asolvent;

b) collapsing at least a portion of the polymeric material about one ormore precursor moieties to form a composite precursor moiety having amean diameter in the range between about 1 nm and about 100 nm;

c) cross-linking the polymeric material of said composite precursormoiety; and

d) modifying at least a portion of said precursor moieties of saidcomposite precursor moiety to form one or more nanoparticles and therebyforming a composite nanoparticle.

“Confined” in this specification means that the nanoparticle issubstantially within the limits of the collapsed polymer's dimensionsand includes, but is not limited to, the situation wherein portions ofthe polymer may be strongly interacting with the nanoparticle within thepolymer dimensions.

As used herein, the term “precursor moiety” refers to a compound orentity at least a portion of which is a component of the eventualnanoparticle formed and includes nanoparticle precursors.

A polymeric material of use in the practice of the present inventionscan be any molecule capable of collapse that contains units of monomers,that can be synthetic or naturally occurring and can be linear,branched, hyperbranched, or dendrimeric. Non-limiting examples ofsuitable polymeric materials are discussed in the various examples,which include, but are not limited to, poly(diallyldimethylammoniumchloride) (PDDA), and polyacrylic acid (PAA), poly(styrene sulfonicacid) (PSS),

It also can be any polymer containing ionized or ionizable moietiesalong its length and is of sufficient length such that the collapsedform has nanometer dimensions. The collapsed form can be of differentmorphologies, such as, for example, spherical, elongated, ormulti-lobed. The dimensions in any direction are anywhere from 0.1 to100 nm, and preferably 1-50 nm.

A wide variety of solvents can be used to form a polymeric solution ofuse in the present inventions. In various embodiments, the polymericsolution is preferably an aqueous solution.

In preferred embodiments of the present inventions, a chosen polymer isdissolved in a suitable solvent to form a solution of the polymer. Thesolvent can be water, an organic solvent or a mixture of two or moresuch solvents. The addition to the solution of the collapsing agentinduces a collapse of the polymer which substantially surrounds, e.g.,confines, a precursor moiety. The collapsing agent can itself be theprecursor moiety. The chosen confined agent, for example a precursormoiety, can be, e.g., an organic or inorganic charged ion or acombination thereof. For example, the confined agent can be an ion froman organic salt, an inorganic salt, or an inorganic salt that is watersoluble where the water soluble inorganic salt is of the form M_(x)A_(y)where M is a metal cation belonging to Groups I to IV of the PeriodicTable possessing a charge +y and A is the counter ion to M with a charge−x or a combination thereof. The confined agent could further comprise amixture of ions from at least two inorganic salts.

Collapsing agents are usually water-soluble inorganic salts, mostpreferably, those that contain metal cations and their correspondinganions, both of which are known to induce a collapse-transition forcertain polymeric materials. Non-limiting examples are Cd(NO₃)₂,Zn(NO₃)₂, Cu(SO₄), Pb(NO₃)₂, Pb(CH₃COO)₂, Ag(NO₃), Mn(SO₄), Ni(NO₃)₂.

A variety of techniques can be used to collapse the polymeric materialaround a precursor moiety. For example, in various embodiments acollapsing agent such as a different solvent, an ionic species (e.g., asalt); or combinations thereof can be used. In various embodiments, itis preferred that the precursor moiety itself serve as a collapsingagent. Multiple collapsing agents can be used.

In various embodiments the at least one collapsing agent preferablycomprises at least one ionic species. Preferably, in variousembodiments, the at least one ionic species is a precursor moiety.

In various embodiments, the precursor moiety comprises at least onemetal cation, complexed metal cation, or complexed metal anion. Invarious embodiments where the precursor moiety comprises a metal cation,complexed metal cation, or complexed metal anion, the modifying step(production means) comprises treating the cation, complexed cation, orcomplexed anion with γ-radiation or an agent selected from a reducingagent or an oxidizing agent to effect production of the nanoparticlecomprising elemental metal confined within the cross-linked, collapsedpolymeric material.

In various embodiments, the precursor moiety comprises two or moredifferent metals. In various embodiments where the precursor moietycomprises two or more different metals, the modifying step comprisesforming an alloy of two or more of the two or more metals.

In various embodiments, the precursor moiety comprises ions selectedfrom a cation, complexed cations, or complexed metal anions of aplurality of metals and the modifying step comprises treating thecations or complexed anions with radiation, for example, γ-radiation, oran agent selected from a reducing agent or an oxidizing agent to effectproduction of the nanoparticle comprising an alloy of said metals,confined within the cross-linked collapsed polymeric material.

In various embodiments, the precursor moiety comprises a metalspecies-containing compound.

By the term “metal species-containing compound” is meant a compoundcontaining a metal or metalloid in any valence state.

In various embodiments of the present inventions having an elementalmetal, alloy comprising a metal, or a metal species-containing compound,the metal is preferably Cd, Zn, Cu, Pb, Ag, Mn, Ni, Au, Mg, Fe, Hg, Ptor a combination thereof.

In various embodiments of the present inventions having a metalspecies-containing compound, said compound containing said metal speciespreferably comprises one or more of a sulphide, selenide, telluride,chloride, bromide, iodide, oxide, hydroxide, phosphate, carbonate,sulphate, chromate and a combination thereof.

In various embodiments, a composite precursor moiety formed by a methodof the present inventions has a mean diameter in the range between about1 nanometer (nm) to about 100 nm. In various embodiments, the compositeprecursor moiety has a mean diameter in one or more of the rangesbetween: (a) about 1 nm to about 10 nm; (b) about 10 nm to about 30 nm;(c) about 15 nm to about 50 nm; and (d) about 50 nm to about 100 nm). Itis to be understood that the term “mean diameter” is not meant to implyany sort of specific symmetry (e.g., spherical, ellipsoidal, etc.) of acomposite precursor moiety. Rather, the composite precursor moiety couldbe highly irregular and asymmetric.

The formation of intra-molecular covalent bonds that effects thecross-linking of the polymeric material can be induced either bychemical means or by irradiation. Chemical means of cross-linking canalso be achieved through the use of multi-dentate molecules ascross-linkers. These molecules contain multiple functional groups thatare complementary to, and, therefore, can form covalent bonds with thefunctional groups on the polyelectrolyte polymeric material. Thesemolecules can be linear, branched, or dendrimeric. For example, amolecule containing multiple amine groups, such as2,2′-ethylenedioxydiethylamine can effect the intramolecularcross-linking of collapsed poly(acrylic acid). The cross-linkingreaction in this case is promoted by the addition of an activatingagent, typically used for amide bond formation, such as a carbodiimide.

The chemical cross-linking can be carried out to derivatize the polymer,such that a fraction of the ionizable groups are converted to groupsthat can be cross-linked through free-radical reactions. An example isto convert some of the carboxylic acid groups of poly(acrylic acid) toallyl esters. The allyl groups can then be reacted to formintramolecular bonds through radical chemistry.

Cross-linking by irradiation can be effected by exposing a solution ofthe collapsed polymer to an electromagnetic radiation source. Theradiation source can be, for example, an excimer laser, a mercury arclamp, a light emitting diode, UV germicidal lamp radiation or gammarays.

A variety of techniques can be used in the present inventions to modifyat least a portion of said precursor moieties of said compositeprecursor moiety to form one or more nanoparticles and thereby form acomposite nanoparticle. These techniques are also referred to as“production means” herein since they are used in the production of thenanoparticle.

Suitable techniques for modifying a precursor moiety to form the desirednanoparticle include, but are not limited to, exposure toelectromagnetic radiation, chemical treatment, and combinations thereof.Examples of suitable electromagnetic radiation exposure, include, forexample γ-radiation, ultraviolet radiation, infrared radiation, etc. Invarious embodiments, the electromagnetic radiation is coherentradiation, such as provided, e.g., by a laser, in others it isincoherent, such as provided, e.g., by a lamp. Examples of chemicaltreatments include, but are not limited to, contacting with an oxidizingagent, contacting with a reducing agent, addition of at least onecounter ion, a compound containing the counter ion, or a precursor tothe counter ion, where the counter ion is a counter ion with respect tothe precursor moiety or a portion thereof. Generally, modification ofthe precursor moiety results in the formation of a nanoparticle that isno longer soluble within the solvent of the polymeric solution.

Reaction either by reduction or oxidation of the ions, ionic precursormoieties, within the cross-linked polymeric material to form thecomposite nanoparticles can be effected through chemical,electrochemical, or photochemical means.

The resultant nanoparticles can be, for example, semiconductor crystals,including, but not limited, to CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, PbS,PbSe, PbTe, CuI, HgS, HgSe, and HgTe. The nanoparticles can also bemetal alloys.

In various embodiments, a composite nanoparticle formed by a method ofthe present inventions has a mean diameter in the range between about 1nanometer (nm) to about 100 nm. In various embodiments, the compositenanoparticle has a mean diameter in one or more of the ranges between:(a) about 1 nm to about 10 nm; (b) about 10 nm to about 30 nm; (c) about15 nm to about 50 nm; and (d) about 50 nm to about 100 nm). It is to beunderstood that the term “mean diameter” is not meant to imply any sortof specific symmetry (e.g., spherical, ellipsoidal, etc.) of a compositenanoparticle. Rather, the composite nanoparticle could be highlyirregular and asymmetric.

In various embodiments, the nanoparticle, formed from a precursormoiety, comprises an alloy of two or more different metals. In variousembodiments where the precursor moiety comprises two or more differentmetals, the modifying step comprises forming an alloy of two or more ofthe two or more metals.

In various embodiments, the nanoparticle, formed from a precursormoiety, comprises a metal species-containing compound. By the term“metal species-containing compound” is meant a compound containing ametal or metalloid in any valence state.

In various embodiments of the present inventions having an elementalmetal, alloy comprising a metal, or a metal species-containing compound,the metal is preferably Cd, Zn, Cu, Pb, Ag, Mn, Ni, Au, Mg, Fe, Hg, Ptor a combination thereof.

In various embodiments of the present inventions having a metalspecies-containing compound, said compound containing said metal speciespreferably comprises one or more of a sulphide, selenide, telluride,chloride, bromide, iodide, oxide, hydroxide, phosphate, carbonate,sulphate, chromate and a combination thereof.

In various aspects, the present inventions provide methods for producinga nanoparticle material, comprising the steps of: (a) providing apolymeric solution comprising a polymeric material and a solvent; (b)collapsing at least a portion of the polymeric material about one ormore precursor moieties to form a composite precursor moiety; (c)cross-linking the polymeric material of said composite precursor moiety;and (d) modifying at least a portion of said precursor moieties of saidcomposite precursor moiety to form one or more nanoparticles having amean diameter in the range between about 1 nm and about 100 nm andthereby forming a composite nanoparticle; and (e) pyrolysing saidcomposite nanoparticle to form a nanoparticle material. In variousembodiments, the pyrolysis conditions are controlled such that thenanoparticle material formed comprises at least a partiallycarbon-coated nanoparticle

In various embodiments, the present inventions provide methods forproducing a metal nanoparticle, comprising pyrolysing the compositenanoparticle prepared by a method of the present inventions describedherein, wherein the metal nanoparticle is an elemental metal, an alloycomprising the metal with at least one other metal, or a metalspecies-containing compound, at a temperature to effective tosubstantially remove the polymeric material.

In various embodiments, the present inventions provide methods forproducing a carbon-coated metal nanoparticle comprising incompletelypyrolysing the composite nanoparticle prepared by a method of thepresent inventions described herein, wherein the metal nanoparticle isselected from an elemental metal, an alloy comprising the metal with atleast one other metal, and a metal species-containing compound, at atemperature to effect production of the carbon-coated metalnanoparticle.

In various aspects, the present inventions provide compositenanoparticles when made by a method or process of one of the inventionsdescribed herein.

In various aspects, the present inventions provide non-confined andwholly or partially carbon-coated metal nanoparticles when made bymethods of the present inventions described herein.

Various embodiments of the present inventions can be of value in theproduction of semiconductor nanoparticles, including, for example,quantum dots such as CdSe, CdS, CdTe, and others. Various embodiments ofthe present inventions can be of value in the production of complexsalts, such as LiFePO₄, and oxide particles, such as Fe₂O₃.

Accordingly, in an various embodiments, the precursor moiety comprisesat least one metal cation, complexed metal cation, or complexed metalanion, and the production means (modifying step) comprises treating themetal cation, complexed cation, or complexed anion with a suitablecounterion or precursor thereof to effect production of the compositenanoparticle comprising a metal species-containing compound.

In various embodiments, the precursor moiety comprises an anion, and themodifying step (production means) comprises treating the anion with asuitable metal counterion or precursor thereof to effect production ofthe composite nanoparticle comprising a metal species-containingcompound.

In various aspects, the modifying step comprises use of a suitablecounterion or precursor thereof to effect production of a semiconductornanoparticle or composite nanoparticle.

In a various aspects, the modifying step comprises use of a suitablecounterion or precursor thereof to effect production of a compositenanoparticle comprising a complex salt.

In a various aspects, modifying step comprises use of a suitablecounterion or precursor thereof to effect production of a nanoparticlecomprising a hydroxide. In a preferred aspect, the hydroxide may besubsequently heated to convert the hydroxide to an oxide.

The aforesaid composite nanoparticles comprising a metalspecies-containing compound, a complex salt, hydroxide, or oxide, asemiconductor entity, can be , in various embodiments, effectivelypyrolysed to substantially remove the polymeric material, or to onlypartially remove the polymeric material to produce, for example, awholly or partially carbon-coated nanoparticle.

Thus, various embodiments of the present inventions relate to methods ofmaking composite nanoparticles and nanoparticles that may have a widevariety of applications in a variety of sectors, including, but notlimited to, biology, analytical and combinatorial chemistry, catalysis,energy and diagnostics. By utilizing starting materials that are readilysoluble in water, the present inventions, in various embodiments, canprovide nanoparticles and composite nanoparticles having uniquecharacteristics applicable in the aforesaid sectors, which nanoparticlesmay be water soluble.

The synthesis routes of various embodiments of the present inventions,include, but are not limited to, synthesis in a “one pot” system in anaqueous medium. The particle size can be controlled, for example, byvarying the molecular weight of the polymer, the degree of internalcross-linking, solution conditions and the amount of collapsing agentadded. The polymer coat can be chosen to have desirable functionalgroups that can impart desirable properties, for example, having thecapability for attachment to molecules, such as proteins or to enhanceor decrease the sticking to substrates.

In various embodiments, the present inventions provide methods formaking water-dispersible composite nanoparticles with inherent chemicalfunctional groups that can be reacted with complementary functionalgroups on other molecules. Water-dispersible, in this context, refers tothe formation of composite nanoparticles that can be prevented fromaggregation in aqueous solution through adjustment of solutionconditions.

In various embodiments, the methods of the present inventions provide acomposite nanoparticle having at least one confined agent substantiallysurrounded by a polymeric material which polymer can be either a linearor branched polyanion or polycation or a combination thereof.

In preferred embodiments of the present inventions, a chosen polymer isdissolved in a suitable solvent to form a solution of the polymer. Thesolvent can be water, an organic solvent or a mixture of two or moresuch solvents. The addition to the solution of the collapsing agentinduces a collapse of the polymer which substantially surrounds, e.g.,confines the agent therein. The chosen confined agent can be an organicor inorganic charged ion or a combination thereof. For example, theconfined agent can be an ion from an organic salt, an inorganic salt, oran inorganic salt that is water soluble where the water solubleinorganic salt is of the form M_(x)A_(y) where M is a metal cationbelonging to Groups I to IV of the Periodic Table possessing a charge +yand A is the counter ion to M with a charge −x or a combination thereof.The confined agent could further comprise a mixture of ions from atleast two inorganic salts.

In various embodiments, to retain the conformation of the collapsedpolymer, cross-linking of the collapsed polymer is achieved by exposingthe polymer to γ-radiation alpha radiation, beta radiation, neutronradiation or UV radiation. Preferably, the UV radiation is UV laserradiation or UV arc lamp radiation. In various embodiments, theintra-molecular cross-links of the intra-molecular cross-linking processare chemically produced, for example, with carbodiimide chemistry with amultifunctional cross-linker.

One preferred embodiment of the present inventions involves theformation of composite nanoparticles by the addition of ions that induceprecipitate formation of the confined agent within the collapsedpolymeric material, wherein the collapsed polymer is intra-molecularlycross-linked. As used herein, “precipitation” of a confined ion refersto modification of the ion to a compound that is substantially insolublein the solvent of the polymeric solution.

Various preferred embodiments of the aspects of the present inventionsinclude, but are not limited to, using polymers dissolved in a solvent,usually water, so as to make a dilute solution. Polymers with ionizablegroups, for example, NH₂, RNH, and COOH can be chosen because of theirwater-solubility under appropriate solution conditions and their abilityto undergo a collapse transition when exposed to certain concentrationsof ions in solution, usually through addition of an inorganic salt. Thecollapse of the polymer brings about the confinement of some of the ionswithin a collapsed polymeric structure. In order to make the collapsedconformation of the polymers permanent, intra-macromolecular bondformation is facilitated either through radiation exposure, through theuse of chemical cross-linkers, or both. In various embodiments, thecollapsed intra-molecular, cross-linked polymer have some of the ionsfrom an inorganic salt confined within the collapsed structure as thebasis for the formation of the composite nanoparticle. The confinedions, for example, can be reduced, oxidized, and/or reacted (e.g. byprecipitation with an external agent), which results in the formation ofthe composite nanoparticle of the inner nanoparticle confined within thecollapsed intra-molecular cross-linked polymeric material. Un-reactedionizable groups, for example, can serve as future sites for furtherchemical modification, dictate the particles solubility in differentmedia, or both.

An ionizable moiety or group is any chemical functional group that canbe rendered charged by adjusting solution conditions, while ionizedmoieties refers to chemical functional groups that are chargedregardless of solution conditions. The ionized or ionizable moiety orgroup can be either cationic or anionic, and can be continuous along anentire chain as in the case of regular polymers, or can be interruptedby blocks containing different functional groups, as in the case ofblock polymers.

In various embodiments, a preferred cationic group is the amino groupand preferred anionic groups are carboxylic acid, sulfonic acid,phosphates, and the like. For cationic polymers, examples arepoly(allylamine), poly(ethyleneimine) poly(diallyldimethylammoniumchloride, and poly(lysine). For anionic polymers, examples arepoly(acrylic acid), poly(styrene sulfonic acid), poly(glutamic acid),etc. Block polymers are made up of blocks of polymers having differentfunctional groups. The block polymers can be made up of blocks of any ofthe mentioned anionic and cationic polymers and another polymer thatimparts a specific desirable property to the block polymer.

In various embodiments, functional groups of the polymeric material canbe used for conjugating the composite nanoparticles to other moleculescontaining complementary functional groups. These molecules can be anymember of affinity-binding pairs such as antigen-antibody, DNA-protein,DNA-DNA, DNA-RNA, biotin-avidin, hapten-antihapten, protein-protein,enzyme-substrate and combinations thereof. These molecules can also beprotein, ligand, oligonucleotide, aptamer, carbohydrate, lipid, or othernanoparticles. An example is the conjugation of poly(acrylicacid)-encased nanoparticles to proteins through amide bond formationbetween amine groups on proteins and the carboxylic acid groups on polyacrylic acid (PAA).

A fraction of the functional groups of the polyelectrolyte polymer canalso be modified to convert them to other functional groups that can beused for conjugation. For example, a hetero bi-functional moleculecontaining an amine group and a latent thiol group can be reacted withpoly(acrylic acid)-encased nanoparticles through amide bond formationthereby converting the carboxylic acid to a thiol group. The thiol groupcan be used for conjugation to other molecules containing thiol-reactivegroups.

The wide variety of potential applications for the compositenanoparticles and nanoparticles, produced by the methods of the presentinvention include, but are not limited to, the absorption of lightenergy selected from the group consisting of UV, visible, and IR light,wherein the composite nanoparticle or nanoparticle are used as pigmentsor are incorporated into an optical device. In various embodiments,after absorbing light energy the composite nanoparticle may be capableof emitting light.

In various embodiments of the present inventions, provided are methodswherein the polymeric material is conjugated to molecules containingfunctional groups for binding to complementary binding partners to forman affinity-binding pair selected from the group having anenzyme-substrate, antigen-antibody, DNA-DNA, DNA-RNA, biotin-avidin,hapten-antihapten and combinations thereof. Preferably, the moleculesare selected from the group consisting of protein, ligand,oligonucleotide, aptamer, and other nanoparticles.

In various embodiments, a composite nanoparticle of the presentinventions may be used, e.g., to enhance spectroscopic techniques,including vibrational spectroscopy.

In various embodiments, provided are methods wherein the compositenanoparticles are further assembled on a surface of a substrate usinglayer-by-layer assembly or further aggregated into three-dimensionalsystems of composite nanoparticles, whereby the three-dimensionalsystems are created on a surface. In various embodiments this substrateis a film.

Accordingly, in various aspects the present inventions provide a coatedsubstrate having a plurality of layers of composite nanoparticles asherein described interspersed between adjacent layers of oppositelycharged compounds.

In various embodiments, a coated substrate as herein described ispreferably coated, with a composite nanoparticle of CdS/PAA and theoppositely charged compound is poly(allylamine) hydrochloride (PAH).

In various embodiments, the present inventions provide use of acomposite nanoparticle as herein described in the production of amulti-layered coated substrate. This substrate could be of value, forexample, as one or more of: (a) a solid substrate comprising catalyticor otherwise reactive nanoparticles; and (b) an optical filter or as anelement in an optical device where the incorporated compositenanoparticles have useful properties.

In various embodiments, the compounds according to the presentinventions could be of value as semiconductor materials, for example, asquantum dots.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects, embodiments, objects, features andadvantages of the present inventions can be more fully understood fromthe following description in conjunction with the accompanying drawings.In the drawings, like reference characters generally refer to likefeatures and structural elements throughout the various figures. Thedrawings are not necessarily to scale, emphasis instead being placedupon illustrating the principles of the present inventions, wherein.

FIG. 1 represents UV-Vis absorption spectra of CdS/PAA compositenanoparticles prepared according to Example 13;

FIG. 2 represents emission spectra of different CdS/PAA compositenanoparticles prepared according to Example 13;

FIG. 3 represents STEM image of CdS/PAA composite nanoparticles preparedaccording to Example 13;

FIG. 4 represents uv-vis absorption and emission spectra of CdSe/PAAcomposite nanoparticles prepared according to Example 14;

FIG. 5 represents uv-vis absorption and emission spectra of(CdSe—CdS)/PAA composite nanoparticles prepared according to Example 15;

FIG. 6 represents uv-vis absorption and emission spectra of CdTe/PAAcomposite nanoparticles prepared according to Example 16;

FIG. 7 represents uv-vis absorption and emission spectra of(CdTe—ZnS)/PAA composite nanoparticles produced according to Example 17;

FIGS. 8( a)-8(c) represent STEM with EDX analysis of LiFePO₄/PAAcomposite nanoparticles produced according Example 18;

FIG. 9 represents a XRD pattern of LiFePO₄/PAA composite nanoparticlesproduced according Example 18;

FIGS. 10( a)-10(c) represents STEM with EDX analysis of Fe₂O₃/PAAcomposite nanoparticles produced according Example 19;

FIG. 11 represents an XRD x-ray diffraction pattern of Fe₂O₃/PAAcomposite nanoparticles produced according to Example 19;

FIG. 12 represents STEM image of ZnO/PAA composite nanoparticles madeaccording to Example 20;

FIG. 13 represents uv-vis absorbance and emission spectra of ZnO/PAAcomposite nanoparticles made according to Example 20;

FIG. 14 represents emission spectra of both CdS/PAA compositenanoparticles coated and non-coated polystyrene prepared according toExample 21;

FIG. 15 represents uv-vis absorption spectra of Ag/PAA compositenanoparticles produced according to Example 22;

FIG. 16 represents a STEM image of Ag/PAA composite nanoparticlesproduced according to Example 22;

FIG. 17 represents uv-vis absorption spectra of Au/PAA compositenanoparticles produced according to Example 23;

FIG. 18 represents STEM image of Au/PAA composite nanoparticles producedaccording to Example 23;

FIG. 19 represents uv-vis spectra of (Au, Ag)/PAA compositenanoparticles produced according to Example 24;

FIGS. 20( a)-20(c) represent STEM with EDX analysis image of (Au,Ag)/PAA composite nanoparticles produced according to Example 24;

FIG. 21 represents uv-vis and emission spectra of CdS/PSS compositenanoparticles produced according to Example 27;

FIG. 22 represents uv-vis and emission spectra of CdS/PDDA compositenanoparticles produced according to Example 28; and

FIG. 23 represents absorbance and emission spectra of CdPbTe/PAAcomposite nanoparticles produced according to Example 36 according tothe present invention;

FIG. 24 absorbance and emission spectra of CdZnTe/PAA compositenanoparticles produced according to Example 37 according to theinvention; and

FIG. 25 absorbance and emission spectra of CdMnTe/PAA compositenanoparticles produced according to Example 38 according to the presentinvention.

FIG. 26 represents UV-vis absorbance spectra of blue colored Ag⁺/PAA-PSSproduced according to Example 41 according to the present invention.

FIG. 27 represents UV-vis absorbance spectra of Ag/PAA-PSS producedaccording to Example 41 according to the present invention.

FIG. 28 represents an absorption profile of ZnS/PAA-PSS_(5%)nanoparticles diluted 10× produced according to Example 43 according tothe present invention.

FIG. 29: represents measurements of fluorescence emission when excitedusing a broadband UV source of (Zn—Cd)S/PAA with different compositionsprepared according to Example 44 according to the present invention.

FIG. 30 represents measurements of viscosity as a function of pH forchitosan according to Example 45 according to the present invention,demonstrating collapse transition.

FIG. 31 represents measurements of the efflux time as a function of NaClconcentration according to Example 45 according to the presentinvention, demonstrating collapse transition.

FIG. 32 schematically represents a Heck coupling reaction catalyzed byPd nanoparticles prepared according to Example 51 according to thepresent invention.

FIG. 33 represents UV-Vis absorbance spectra of ZnO nanoparticlesprepared according to Example 53 according to the present invention.

FIG. 34 represents UV-Vis absorption spectrum of the ZnO nanoparticlesafter heating according to Example 53 according to the presentinvention.

FIG. 35 represents a TEM image of the particles after heating to 450° C.according to Example 53 according to the present invention.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS EXAMPLES

In the following examples, the term

(a) “M^(y+)/polymer refers to the collapsed polymeric material with themetal cation M^(y+), wherein M is the stated metal in the example; and

(b) A^(x−)/polymer refers to the collapsed polymeric material collapsedwith the anion A^(x−).

In the case of multiple cations or anions used to collapse a singlepolymer, the different metal cations and anions will be separated by acomma “,” as in the case (M₁ ^(y1+), M₂ ^(y2), etc. . . . )/Polymer and(A₁ ^(x1−), A₂ ^(x2−), etc. . . . )/Polymer (e.g. Cd²⁺/PAA, Cl⁻/PDDA,etc.). Nanoparticles formed from the metal ions will be designated asM_(1 xl) A_(1 y1)/Polymer (e.g. CdS/PAA, (CdS, PbS)/PAA, etc).Nanoparticles formed from the metal ions that have been treated withanother agent to form a different material will be designated by a “−”as in (M_(1x1)A₁y₁-M_(2 y2) A_(2 y2))/Polymer (e.g. (CdSe—CdS)/PAA,(CdTe—ZnS)/PAA, etc).

Example 1 Polycation Collapse with (−1) Anion

In a plastic 400.0 ml beaker, 3.0 ml of poly(diallyldimethylammoniumchloride) (PDDA) [Sigma, Average M_(W) 400-500K, 20 wt % in water] wasdiluted to 300 ml with deionized water. The solution was stirred for 10minutes. 5.0 ml aliquots were obtained, and placed in 20 mlscintillation vials. To each was added dropwise with vigorous stirring5.0 ml of aqueous NaCl solutions of different concentrations (2 mM-60mM) yielding 10 mL of Cl⁻/PDDA solutions with different [Cl⁻] between 1and 50 mM and a final PDDA concentration of 1 mg/ml. The relativeviscosity of each solution was measured with an Ostwald viscometer. Theviscosity as a function of NaCl concentration changed suddenly atapproximately 10 mM; this was taken as the PDDA collapse point with Cl⁻,such that at lower concentrations, the PDDA is primarily in an extendedconfiguration.

Example 2 Polycation Collapse with (−2) Anion

In a plastic 400.0 ml beaker, 3.0 ml of poly(diallyldimethylammoniumchloride) (PDDA) [Sigma, Average M_(W) 400-500K, 20 wt % in water] wasdiluted to 300 ml with deionized water. The solution was stirred for 10minutes. 5.0 ml aliquots were obtained, and placed in 20 mlscintillation vials. To each was added dropwise with vigorous stirring5.0 ml of aqueous Na₂SO₄ solutions of different concentrations (2 mM-20mM) yielding 10 mL of SO₄ ²⁻/PDDA solutions with different [SO₄ ²⁻]between 1 and 10 mM and a final PDDA concentration of 1 mg/ml. Therelative viscosity of each solution was measured with an Ostwaldviscometer. The viscosity as a function of NaCl concentration changedsuddenly at approximately 3 mM; this was taken as the PDDA collapsepoint with SO₄ ²⁻, such that at lower concentrations, the PDDA isprimarily in an extended configuration.

Example 2 Polycation Collapse with (−3) Anion

In a plastic 400.0 ml beaker, 15 ml of poly(diallyldimethylammoniumchloride) (PDDA) [Sigma, Average M_(W) 400-500K, 20 wt % in water] wasdiluted to 300 ml with deionized water. The solution was stirred for 10minutes. 5.0 ml aliquots were obtained, and placed in 20 mlscintillation vials. To each was added dropwise with vigorous stirring5.0 ml of aqueous Na₃PO₄ solutions of different concentrations (2 mM-50mM) yielding 10 mL of PO₄ ³⁻/PDDA solutions with different [PO₄ ³⁻]between 1 and 25 mM and a final PDDA concentration of 5 mg/ml. Therelative viscosity of each solution was measured with an Ostwaldviscometer. The viscosity as a function of NaCl concentration changedsuddenly at approximately 2 mM; this was taken as the PDDA collapsepoint with PO₄ ³⁻, such that at lower concentrations, the PDDA isprimarily in an extended configuration.

Example 4 Polyanion Collapse with (+1) Cation

In a 400 ml plastic beaker, 400.0 mg of (PAA) (Sigma, Average M_(V) 1.2million) was dissolved in 200 ml deionized water. The plastic beaker wasimmersed in a hot water bath (approximately 80-90° C.) and was stirredvigorously for at least 30 minutes or until all of the solid PAA hasdissolved. Once the solution has cooled to room temperature, the pH wasadjusted to 6.8 using 0.1 M NaOH. pH measurements were done using narrowrange pH paper. 5 ml aliquots of the pH adjusted PAA were obtained andto each was added 5.0 ml aliquots were obtained, and placed in 20 mlscintillation vials. To each was added dropwise with vigorous stirring5.0 ml of aqueous NaCl solutions of different concentrations (0.2mM-10.0 mM) yielding 10 mL of Na⁺/PDDA solutions with different [Na⁺]between 0.1 mM and 5.0 mM and a final PAA concentration of 1 mg/ml. Therelative viscosity of each solution was measured with an Ostwaldviscometer. The viscosity as a function of NaCl concentration changedsuddenly at approximately 2 mM; this was taken as the PAA collapse pointwith Na⁺, such that at lower concentrations, the PAA is primarily in anextended configuration.

Example 5 Polyanion Collapse with (+2) Cation

In a 400 ml plastic beaker, 400.0 mg of PAA (Sigma, Average M_(W) 1.2million) was dissolved in 200 ml deionized water. The plastic beaker wasimmersed in a hot water bath (approximately 80-90° C.) and was stirredvigorously for at least 30 minutes or until all of the solid PAA hasdissolved. Once the solution has cooled to room temperature, the pH wasadjusted to 6.8 using 0.1 M NaOH. pH measurements were done using narrowrange pH paper. 5 ml aliquots of the pH adjusted PAA were obtained andto each was added 5.0 ml aliquots were obtained, and placed in 20 mlscintillation vials. To each was added dropwise with vigorous stirring5.0 ml of aqueous Cd(NO₃)₂ solutions of different concentrations (0.1mM-6.0 mM) yielding 10 mL of Cd²⁺/PAA solutions with different [Cd²⁺]between 0.1 mM and 3.0 mM and a final PAA concentration of 1 mg/ml. Therelative viscosity of each solution was measured with an Ostwaldviscometer. The viscosity as a function of Cd(NO₃)₂ concentrationchanged suddenly at between 1-2 mM; this was taken as the PAA collapsepoint with Cd²⁺, such that at lower concentrations, the PAA is primarilyin an extended configuration. Addition of more Cd(NO₃)₂ such that thefinal concentration >2 mM caused a white precipitate to form. Solutionswith a final concentration of 1.2 mM Cd(NO₃)₂ and approx 0.7 mg/ml PAAwere then prepared for use in subsequent examples below; this solutionis referred to as Cd²⁺/PAA in this work.

Example 6 Polyanion Collapse with (+3) Cation

In a 400 ml plastic beaker, 400.0 mg of poly(styrene sulfonic acid)(PSS) (Alfa Aesar, Average M_(W) 1 million) was dissolved in 200 mldeionized water. 5 ml aliquots of the PSS solution were obtained, andplaced in 20 ml scintillation vials. To each was added dropwise withvigorous stirring 5.0 ml of aqueous solutions containing FeCl₃ ofdifferent concentrations (0.2 mM-20.0 mM) yielding 10 mL of Fe³⁺/PDDAsolutions with different [Fe³⁺] between 0.1 mM and 10.0 mM and a finalPSS concentration of 1 mg/ml. The relative viscosity of each solutionwas measured with an Ostwald viscometer. The viscosity as a function ofFeCl₃ concentration changed suddenly at approximately 2 mM; this wastaken as the PSS collapse point with Fe³⁺ such that at lowerconcentrations, the PSS is primarily in an extended configuration.

Example 7 Polyanion Collapse with 2 Cations

In a 400 ml plastic beaker, 400.0 mg of PAA (Sigma, Average M_(V) 1.2million) was dissolved in 200 ml deionized water. The plastic beaker wasimmersed in a hot water bath (approximately 80-90° C.) and was stirredvigorously for at least 30 minutes or until all of the solid PAA hasdissolved. Once the solution had cooled to room temperature, the pH wasadjusted to 6.8 using 0.1 M NaOH. pH measurements were done using narrowrange pH paper. 5.0 ml aliquots were obtained, and placed in 20 mlscintillation vials. To each was added dropwise with vigorous stirring5.0 ml of aqueous solutions containing FeCl₂ and LiCl at a mole ratio of(2:1) of different concentrations* (0.2 mM-8.0 mM) yielding 10 mL of(2Fe²⁺, Li⁺)/PAA solutions with different [2Fe²⁺, Li²⁺] between 0.1 mMand 4.0 mM and a final PAA concentration of 1 mg/ml. The relativeviscosity of each solution was measured with an Ostwald viscometer. Theviscosity as a function of FeCl₂ and LiCl concentration changed suddenlyat approximately 0.3 mM; this was taken as the PAA collapse point with2Fe²⁺, Li⁺ such that at lower concentrations, the PAA is primarily in anextended configuration. *concentrations refer to the total concentrationof both metal ions combined

Example 8 Preparation of Cd²⁺/PAA Crosslinked Composite NanoparticlesAccording to the Invention using Mercury Arc Lamp

A solution of Cd²⁺/PAA was prepared by dropwise addition of 10 ml of0.005M Cd(NO₃)₂ solution to 10 ml of 2 mg/ml aqueous solution of PAA(Sigma, Ave M_(W) 1.2 million PAA, pH adjusted to 6.8 with 0.1 M NaOH).The solution was exposed to light from a 200 W mercury arc lamp forapproximately 1 hour to effect collapse, while undergoing vigorousstirring. The irradiated solution was then dialyzed against deionizedwater for 3 hours. The dialysis is expected to substantially reduce theconcentration of ions in solution, thus reversing the polymer collapse.However, it was found that the solution viscosity remains unchanged(still low), indicating that the collapsed configuration is retained,and that the collapsed polymer has been crosslinked to remain in thecollapsed configuration. An aliquot of the solution was cast onto micaand allowed to air dry. Atomic force microscopy imaging indicated thepresence of particles 10-25 nm in size.

Example 9 Preparation of Zn²⁺/PAA and Cd²⁺/PAA Crosslinked CompositeNanoparticles According to the Invention using Laser Irradiation

A solution of Zn²⁺/PAA was prepared by dropwise addition of 10 ml of0.005M Zn(NO₃)₂ solution to 10 ml of 2 mg/ml aqueous solution of PAA(Sigma, Ave M_(W) 1.2 million PAA, pH adjusted to 6.8 with 0.1 M NaOH)with vigorous stirring. The solution was exposed to 5000 pulses from anexcimer laser source (10 mJ/cm³) while undergoing vigorous stirring. Thelaser irradiated solution was then dialyzed against deionized water for3 hours, changing the deionized water reservoir every hour. The solutionviscosity remained unchanged by dialysis, indicating that the collapsedconfiguration is retained.

A solution of Cd²⁺/PAA was prepared by dropwise addition of 10 ml of0.005M Cd(NO₃)₂ solution to 10 ml of 2 mg/ml aqueous solution of PAA(Sigma, Ave M_(W) 1.2 million PAA, pH adjusted to 6.8 with 0.1 M NaOH)with vigorous stirring. The solution was exposed to 5000 pulses from anexcimer laser source (10 mJ/cm³) while undergoing vigorous stirring. Thelaser irradiated solution was then dialyzed against deionized water for3 hours, changing the deionized water reservoir every hour. The solutionviscosity remained unchanged by dialysis, indicating that the collapsedconfiguration is retained.

Example 10 Preparation of Zn²⁺/PAA Crosslinked Composite NanoparticlesAccording to the Invention using Chemical Crosslinking Agent

Zn²⁺/PAA solution was prepared according to example 9. 2.0 ml ofZn²⁺/PAA was placed in a 5 ml glass vial and 160 μl of a solution thatwas 26.4 mg/mL in 1-Ethyl-N′(3-dimethylaminopropyl)carbodiimide (EDC)and 33.45 mM in 2,2′-(Ethylenedioxy)bis-(ethylamine) (EDE) was addedunder constant stirring. The resulting solution was stirred for 12 hoursand was then dialyzed against deionized water for 3 hours, changing thedeionized water reservoir every hour. Zn²⁺/PAA that was not treated withthe EDC/EDE solution was also dialyzed against deionized water for 3hours, changing the deionized water reservoir every hour. Afterdialysis, the viscosity of the EDC/EDE treated Zn²⁺/PAA solution wasmuch lower than that of an untreated Zn²⁺/PAA solution. This indicatesthat the collapsed configuration is retained after Zn²⁺/PAA was treatedwith the EDC/EDE solution.

Example 11 Polyacrylic Acid Crosslinking with Gamma Radiation to ProduceCd²⁺/PAA Composite Nanoparticles According to the Invention

20 ml of Cd²⁺/PAA, prepared as described in Example 5, was placed in a20 ml scintillation vial. To this, 200 μl of isopropanol (ACS grade) wasadded. The vial was sealed with a rubber septum and was vortexed for 10seconds. The solution was exposed to a total dose of ˜15 kGy of gammaradiation at a dose rate of 3.3 kGy/hr. The irradiated solution was thendialyzed against deionized water for 3 hours, changing the deionizedwater reservoir every hour. Similarly, Cd²⁺/PAA that was not exposed togamma radiation was also dialyzed in a similar manner. After dialysis,the viscosity of the collapsed irradiated, dialyzed solution was muchlower than that of a collapsed, un-irradiated solution. Na⁺/PAA preparedaccording to example 4, [Na⁺]=2 mM, was also exposed to the same gammaradiation dose, and similarly the viscosity of the collapsed irradiated,dialyzed Na⁺/PAA solution was much lower than that of a collapsed,un-irradiated solution.

Example 12 Polyacrylic Acid Crosslinking with 4 G25T8 Germicidal Lampsto Produce Cd²⁺/PAA Composite Nanoparticles According to the Invention

20 ml of Cd²⁺/PAA was prepared according to Example 5 was placed in a50.0 ml glass beaker. The solution was exposed to 4 G25T8 germicidal UVlamps (approximate power is 12 μW/mm²) for approximately 1.5-2 hoursunder vigorous stirring. The irradiated solution was then dialyzedagainst deionized water for 3 hours, changing the deionized waterreservoir every hour. Cd²⁺/PAA that was not exposed to the UV lamp wasalso dialyzed in a similar manner. The viscosity of the irradiated,dialyzed Cd²⁺/PAA solution was much lower than that of a Cd²⁺/PAAsolution that was not exposed to the UV lamp. Collapsed PAA withZn(NO₃)₂, Pb(NO₃)₂, Cd/Pb(NO₃)₂, Zn/Cd(NO₃)₂, FeCl₂, LiCI, FeCl₃,Co(SO₄), Cu(SO₄), Mn(SO₄), Ni(CH₃COOH), Zn(NO₃)₂/MgCl₂ was also UVirradiated in a similar manner and the viscosity of the collapsedirradiated, dialyzed solutions were much lower than that of a collapsed,un-irradiated solutions. These solutions were filterable using a 0.2 μmnylon syringe filter.

Example 13 CdS/PAA Composite Nanoparticles According to the Invention

20 ml of crosslinked Cd²⁺/PAA composite nanoparticles was preparedaccording to example 12 and was placed in a 50 ml glass beaker. Undervigorous stirring, 20.0 ml of 0.60 mM Na₂S solution was added dropwiseat a rate of 2 ml/min using a syringe pump. The resulting solution wasyellow in color. Absorbance and emission spectra of the resultingsolution are shown in FIG. 1. The maximum emission wavelength can betuned to different frequencies by varying the ratio of Na₂S to theamount to Cd²⁺ ions present in the Cd²⁺/PAA solution. This is shown inFIG. 2. A red shift in the Emission_(max) is observed as more Na₂S isadded. Scanning Transmission Electron microscopy images of the CdS/PAAprepared are shown in FIG. 3.

Example 14 CdSe/PAA Composite Nanoparticles According to the Invention

300 mL of Cd²⁺/PAA was prepared according to Example 5. The pH of thesolution adjusted to ˜8.5-9.0 with 0.1 M NaOH and was bubbled withN_(2(g)) for 30 minutes in a 500 ml round bottom flask. 18.2 mg of1,1′-dimethylselenourea was dissolved in 5 ml of degassed, deionizedwater and was sealed with a septa in a 5 ml glass vial. Using a 5 mlsyringe, 4.1 ml of this dimethlyselenourea solution was added to theCd²⁺/PAA under N₂ atmosphere. The resulting solution was stirred for 10minutes and then heated on a heating mantle to a temperature ofapproximately 80° C. for 1 hour. After one hour, the solution wasallowed to cool. The resulting solution has an absorption and emissionspectra shown in FIG. 4.

Example 15 (CdSe—CdS)/PAA Composite Nanoparticles According to theInvention

150 ml of CdSe/PAA nanoparticles produced according to Example 14 wasplaced in a 250 ml round bottom flask. 125.0 ml of 0.30 M thioacetamidein water was added to the flask containing the CdSe/PAA nanoparticles.The resulting mixture was stirred vigorously for 5 minutes, and was thenheated to 80° C. on a heating mantle with very light stirring for 24hours. The absorption and emission spectra of the resulting(CdSe—CdS)/PAA composite nanoparticles are shown in FIG. 5.

Example 16 CdTe/PAA Composite Nanoparticles According to the Invention

Under ambient conditions, 300 ml of Cd²⁺/PAA produced according toExample 12 was placed in a 500 ml round bottom flask. To this solution,0.156 g of NaBH₄ and 0.312 g of trisodium citrate was added while thesolution was being stirred. Immediately after the addition of theborohydride and the citrate, 12.5 ml of 0.01M NaTeO₃ was added. Uponaddition of the NaTeO₃ solution, the solution develops a yellow color.The solution was then refluxed for approximately 20 hours to allowCdTe/PAA nanoparticles to form. The absorption and emission spectra ofthe resulting solution after 20 hours of reflux is shown in FIG. 6.

Example 17 (CdTe—ZnS)/PAA Composite Nanoparticles According to theInvention

In 50 a ml falcon tube, 1.7 ml of 3M NaCl was added to 15 ml CdTe/PAAnanoparticles particles formed according to Example 16. The resultingmixture was vortexed for 10 seconds after which 30 ml of absoluteethanol was added and was centrifuged at 8500 rpm for 15 minutes. Aftercentrifugation, the brown pellet formed at the bottom of the falcon tubewas rinsed with 20 ml 70% ethanol. The resulting solution wascentrifuged at 8500 rpm for 10 mins. The brown pellet was isolated andresuspended in 15 ml deionized water. To 10 ml of the resuspendedCdTe/PAA nanoparticles, 278 μL of 24 mM Zn(NO₃)₂ was added. The solutionwas stirred for 10 minutes after which 167 μL 39.5 mM Na₂S was added.After 10 minutes of stirring, a second 278 μL of 24 mM Zn(NO₃)₂ wasadded. The solution was stirred for 10 minutes after which 167 μL 39.5mM Na₂S was added. After 10 more minutes of stirring, a third 278 μL of24 mM Zn(NO₃)₂ was added. The solution was stirred for 10 minutes afterwhich 167 μL 39.5 mM Na₂S was added. The solution was left in a 50 mlfalcon tube for at least 3 days before taking the emission spectra. Theresulting solution's absorption and emission spectra after 3 days isshown in FIG. 7.

Example 18 Formation of LiFePO₄/PAA Composite Nanoparticles According tothe Invention

A 20 ml solution of (Fe²⁺, Li⁺)/PAA was prepared according to Example 7with some modifications. Briefly, in a 400 ml plastic beaker, 400.0 mgof PAA (Sigma, Average M_(V) 1.2 million) was dissolved in 200 mldeionized water. The plastic beaker was immersed in a hot water bath(approximately 80-90° C.) and was stirred vigorously for at least 30minutes or until all of the solid PAA has dissolved. Once the solutionhas cooled to room temperature, the pH was adjusted to 3.0 using 0.1 MHNO₃. pH measurements were done using narrow range pH paper. 10.0 ml ofthis PAA solution was taken and placed in a 50 ml glass beaker to which10.0 ml of a solution that was 6.7 mM in both FeCl₂ and LiCl was addeddropwise with vigorous stirring. The solution was crosslinked for 1.5hours under 4 G25T8 Germicidal lamps. 5.0 ml of a 13 mM NH₄H₂PO₄ wasthen added to the UV exposed (Fe²⁺, Li⁺)/PAA. The solvent (water) of theresulting solution was removed using a rotary evaporator. When all ofthe solvent was removed, a light green colored residue remained and wasthen dried under vacuum for 12 hours. This light green residue wasplaced in tube furnace and was heated under N₂ atmosphere for 12 hoursat 600° C. After 12 hours of heating in the furnace, the light greenresidue tuned black. The STEM images with EDX analysis of theLiFePO₄/PAA composite nanoparticle are shown in FIG. 8. FIG. 8 a is aSTEM image of LiFePO₄/PAA prepared according to the present invention,and wherein FIG. 8 b shows the cross-sectional abundance of phosphorousalong the scanned line in FIG. 8 a acquired using electron dispersivex-rays; and FIG. 8 c shows the cross-sectional abundance of iron alongthe scanned line in FIG. 8 a acquired using electron dispersive x-rays.The XRD pattern for the LiFePO₄/PAA composite nanoparticle is shown inFIG. 9.

Example 19 Formation of Fe₂O₃/PAA Composite Nanoparticles According tothe Invention

Fe₂O₃/PAA is formed by following exactly Example 18 with only onemodification. The pH of the PAA should be adjusted to pH 6.8 instead ofpH 3.0 using 0.1M NaOH before adding the FeCl₂ and LiCl solution. Therest of the procedure remains the same. Surprisingly, this singlemodification leads to the formation of Fe₂O₃/PAA instead of LiFePO₄/PAA.The STEM images with EDX analysis of the LiFePO₄/PAA nanocompositeparticles are shown in FIG. 10. FIG. 10 a is a STEM image Fe₂O₃/PAAnanocomposite prepared according to the present invention, and whereinFIG. 10 b shows the cross-sectional abundance of iron along the scannedline in FIG. 10 a acquired using electron dispersive x-rays; and FIG. 10c shows the cross-sectional abundance of phosphorous along the scannedline in FIG. 10 a acquired using electron dispersive x-rays. The XRDpattern is shown in FIG. 11, wherein H is hematite, alpha-Fe203 and M isdefect spinal structure of magnetite, gamma-Fe203, maghemite. Note thatalthough the EDX images show the presence of phosphate, the XRD patternsuggests that Fe₂O₃ is present and not LiFePO₄.

Example 20 Formation of ZnO/PAA Composites Nanoparticles According tothe Invention

A 20 ml solution of Zn²⁺/PAA was prepared by dropwise addition of 10 mlof 0.005M Zn(NO₃)₂ solution to 10 ml of 2 mg/ml aqueous solution of PAA(Sigma, Ave M_(W) 1.2 million PAA, pH adjusted to 6.8 with 0.1 M NaOH)with vigorous stirring. The solution was exposed to UV radiation for 1.5hours under 4 G25T8 Germicidal lamps as in Example 12. The pH UV exposedZn²⁺/PAA was adjusted to pH 11.0 with 0.1 M NaOH, and then refluxed for1 hour. After reflux, the solution turns slightly cloudy. Theabsorbance, emission spectra and STEM image are shown in FIG. 12 and theabsorbance and emission spectra are shown in FIG. 13.

Example 21 Incorporation of CdS/PAA Composite Nanoparticles According tothe Invention into Layer-by-Layer Thin Films

Polystyrene substrates were sonicated in 0.01M sodium dodecyl sulfate+0.1M HCl solution for 3 minutes, rinsed with distilled water, and driedwith nitrogen. Layer by Layer (LbL) thin films were formed by immersingthe substrate in 1 mg/ml PAH (poly(allylamine) hydrochloride) in 0.1MNaCl for 5 minutes, followed by a 5 minute rinse in 0.1M NaCl, thenimmersed in a solution of CdS/PAA nanoparticle solution (preparedaccording Example 13) for 5 minutes, then rinsed in 0.1 M NaCl solutionfor 5 minutes. This process was repeated 100 times. Emission spectra ofthe polystyrene substrate coated with the LbL thin films of PAH:CdS/PAAcomposite nanoparticles is shown in FIG. 14.

Example 22 Ag/PAA Composite Nanoparticles According to the Invention

20 ml of Ag⁺/PAA was made according to Example 4. Briefly, in a 400 mlplastic beaker, 400.0 mg of PAA (Sigma, Average M_(V) 1.2 million) wasdissolved in 200 ml deionized water. The plastic beaker was immersed ina hot water bath (approximately 80-90° C.) and was stirred vigorouslyfor at least 30 minutes or until all of the solid PAA has dissolved.Once the solution has cooled to room temperature, the pH was adjusted to6.8 using 0.1 M NaOH. pH measurements were done using narrow range pHpaper. 10.0 ml of this PAA solution was placed in a 20 ml scintillationvial and to this, 10 ml of 4.0 mM AgNO₃ solution was added drop wiseunder constant stirring. 0.5 mL of 2-propanol was added to the mixture.The final solution volume was 20 mL. The vials were sealed with rubbersepta and subjected to ⁶⁰Co irradiation using a gamma cell type G.C. 220with a dose rate of 3.3 kGy/hr, at a total dose of 15 kGy. The UV-visspectra and STEM images of the resulting Ag/PAA composite nanoparticlesare shown in FIGS. 15 and 16, respectively.

Example 23 Au/PAA Composite Nanoparticles According to the Invention

20 ml of Au³⁺/PAA was made according to Example 4. Briefly, in a 400 mlplastic beaker, 400.0 mg of PAA (Sigma, Average M_(V) 1.2 million) wasdissolved in 200 ml deionized water. The plastic beaker was immersed ina hot water bath (approximately 80-90° C.) and was stirred vigorouslyfor at least 30 minutes or until all of the solid PAA has dissolved.Once the solution has cooled to room temperature, the pH was adjusted to6.8 using 0.1 M NaOH. pH measurements were done using narrow range pHpaper. 10.0 ml of this PAA solution was placed in a 20 ml scintillationvial, and to this 10 ml of 4.0 mM HAuCl₃ solution was added drop wiseunder constant stirring. 0.5 mL of 2-propanol was added to the mixture.The final solution volume was 20 mL. The vials were sealed with rubbersepta and subjected to ⁶⁰Co irradiation using a gamma cell type G.C. 220with a dose rate of 3.3 kGy/hr, at a total dose of 15 kGy. The UV-visspectra and STEM images of the resulting Au/PAA composite nanoparticlesare shown in FIGS. 17 and 18, respectively.

Example 24 (Au, Ag)/PAA Composite Nanoparticles According to theInvention

20 ml of (Ag⁺, Au³⁺)/PAA was made according to Example 4. Briefly, in a400 ml plastic beaker, 400.0 mg of PAA (Sigma, Average M_(V) 1.2million) was dissolved in 200 ml deionized water. The plastic beaker wasimmersed in a hot water bath (approximately 80-90° C.) and was stirredvigorously for at least 30 minutes or until all of the solid PAA hasdissolved. Once the solution has cooled to room temperature, the pH wasadjusted to 6.8 using 0.1 M NaOH. pH measurements were done using narrowrange pH paper. 10.0 ml of this PAA solution was placed in a 20 mlscintillation vial, and to this 5 ml of 4.0 mM HAuCl₃ solution was addeddrop wise under constant stirring. This was then followed by the dropwise addition of 5.0 ml 4 mM Ag(NO₃), and finally the addition of 0.5 mlof 2-propanol. The final solution volume was 20 mL. The solution wasexposed to 4 G25T8 germicidal UV lamps (approximate power is 12 μW/mm²)for approximately 1.5-2 hours under vigorous stirring. Afterirradiation, the solution changed from colorless to light purple. TheUV-vis spectra and STEM images of the resulting (Au.Ag)/PAA compositenanoparticles are shown in FIGS. 19 and 20, respectively. FIG. 20 a is aSTEM image (Au, Ag)/PAA nanocomposite prepared according to the presentinvention; and wherein FIG. 20 b shows the cross-sectional abundance ofsilver along the scanned line in FIG. 20 a acquired using electrondispersive x-rays; and FIG. 20 c shows the cross-sectional abundance ofgold along the scanned line in FIG. 20 a acquired using electrondispersive x-rays.

Example 25 Formation of CdSePAA-Fluorescein Conjugate According to theInvention

In a 1.5 mL microfuge tube, 400 μL of CdSePAA (−0.2 mg/mL in ddH₂O) wascombined with 4.9 mg 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide(EDC) and 6 mg N-hydroxysuccinimide (NHS) in 500 μL of ddH₂O. 100 μL of250 mM 2-morpholinoethanesulfonic acid (MES) (pH ˜6.5) was added. Andfinally, 20 μL of 5 mg/mL fluorescein in N,N-dimethylformamide (DMF) wasalso added. The tube containing this mixture was wrapped in aluminumfoil and placed on a rotating table for ˜20 h at room temperature. Theresulting mix was placed in a 10 kDa MWCO dialysis bag and dialyzedagainst ddH₂O. The dialysis solution (˜200 fold dilution each time) waschanged five times over a period of ˜24 h. The solution remaining in thedialysis bag was recovered and centrifuged for 10 min at 15,000 RCF. Abrown pellet is found after the centrifugation. The fluorescentsupernatant was transferred to a new microfuge tube and further purifiedby precipitation with the addition of ˜ 1/10 volume of 3M sodium acetate(pH ˜5.5) and 2× volume of absolute ethanol. The resulting fluorescentprecipitate was then isolated by centrifugation for 10 min at 15,000 RCFand resuspended in 200 μL ddH₂O.

The presence of fluorescein conjugated to CdSePAA was confirmed by gelpermeation chromatography using a fluorescence detector (excitation at480 nm and emission at 515 nm).

Example 26 Formation of CdSePAA-BSA Conjugate According to the Invention

In a 1.5 mL microfuge tube, 900 μL of CdSe/PAA (˜0.2 mg/mL in ddH₂O) wascombined with 5.3 mg EDC and 10.8 mg NHS in 100 μL of 250 mM MES (pH˜6.5). And finally, 5.1 mg bovine serum albumin (BSA) was also added.The tube containing this mixture was placed on a rotating table for ˜19h at room temperature. The resulting mix was centrifuged for 10 min at15,000 RCF. ˜500 μL of the supernatant was transferred to a 100 kDa MWCOcentrifugal filter and centrifuged for 12 min at 14,000 RCF. Theresulting filtrate was discarded, and the retenate was resuspended in500 μL of ddH₂O in the same filter and centrifuged again. This wasrepeated three more times. The final retenate was recovered forcharacterization.

Removal of unconjugated BSA using the 100 kDa MWCO filter was confirmedby gel permeation chromatography. And the presence of BSA conjugated toCdSe/PAA remaining in the retenate was confirmed by assay with BioRadprotein reagent.

Example 27 CdS/PSS Composite Nanoparticles According to the Invention

400 mg of Poly(styrene sulfonic acid) sodium salt (Alfa Aesar, Ave M_(W)1 million) was dissolved in 200.0 ml deionized water. 20.0 ml of thissolution was placed in an 80 ml vial and to this, 20.0 ml 4.8 mMCd(NO₃)₂ solution was added dropwise with vigorous stirring. Thesolution was exposed to 4 G25T8 germicidal UV lamps (approximate UVpower is 12 μW/mm²) for 1 hour under vigorous stirring. CdS was formedby adding 0.5 ml 1.4 mM Na₂S to 0.5 ml of the irradiated Cd²⁺/PSSsolution. UV-visible absorbance and emission spectra are shown in FIG.21.

Example 28 CdS/PDDA Nanoparticles

15.0 ml of poly(diallyldimethylammonium chloride) (PDDA) [Sigma, AverageM_(W) 400-500K, 20 wt % in water] was diluted to 300 ml with deionizedwater. The solution was stirred for 10 minutes. 5.0 ml of this solutionwas diluted to 25.0 ml with deionized water in a 80 ml glass beaker. Tothis solution, 25.0 ml of 4 mM Na₂S was added dropwise with vigorousstirring. The solution was exposed to 4 G25T8 germicidal UV lamps(approximate UV power is 12 μW/mm²) for 1 hour under vigorous stirring.CdS/PDDA was formed by adding 0.50 ml of 2.68 mM Cd(NO₃)₂ to 0.50 ml ofirradiated S²⁻/PDDA. UV-visible absorbance and emission spectra areshown in FIG. 22.

Example 29 Polyanion Collapse with Cd²⁺/Pb²⁺ Cations

In a 400 mL plastic beaker, 400.0 mg of PAA (Sigma, Average M_(V) 1.2million) was dissolved in 200 mL deionized water. The plastic beaker wasimmersed in a hot water bath (approximately 80-90° C.) and was stirredvigorously for at least 30 minutes or until all of the solid PAA haddissolved. Once the solution had cooled to room temperature, the pH wasadjusted to 6.8 using 0.1 M NaOH. pH measurements were done usingnarrow-range pH paper. 25 mL of a Cd_(x)Pb_(1-X)(NO₃)₂ solution wasprepared by the addition of 5 mM Cd(NO₃)₂ and 5 mM Pb(NO₃)₂ saltsolutions in various proportions, where x=0.1, 0.2, 0.3, 0.4, 0.5, 0.6,. . . , 1. The total concentration of metal ions in the final solutionwas 5 mM. 20 mL of the pH-adjusted PAA and 25 mL of deionized water wereobtained and placed in a 100 mL beaker. 15 mL of the metal solution wasthen added dropwise under vigorous stirring to yield 60 mL of a Cd_(x)²⁺Pb_(1-x) ²⁺/PAA solution with a final [Cd_(x) ²⁺Pb_(1-x) ²⁺] of 1.25mM and final PAA concentration of 0.67 mg/mL.

Example 30 Polyanion Collapse with Cd²⁺—Mg^(t+)(10%) Cations

In a 400 mL plastic beaker, 400.0 mg of PAA (Sigma, Average M_(V) 1.2million) was dissolved in 200 mL deionized water. The plastic beaker wasimmersed in a hot water bath (approximately 80-90° C.) and was stirredvigorously for at least 30 minutes or until all of the solid PAA haddissolved. Once the solution had cooled to room temperature, the pH wasadjusted to 6.8 using 0.1 M NaOH. pH measurements were done usingnarrow-range pH paper. 25 mL of a Cd_(0.9)Mg_(0.1)(NO₃)₂ solution wasprepared by mixing together of 22.5 mL and 2.5 mL of 5 mM Cd(NO₃)₂ and 5mM Mg(NO₃)₂ solutions, respectively. The total concentration of metalions in solution was 5 mM. 20 mL of the pH-adjusted PAA and 25 mL ofdeionized water were obtained and placed in a 100 mL beaker. 15 mL ofthe metal solution was then added dropwise under vigorous stirring toyield 60 mL of a Cd_(0.9) ²⁺Mg_(0.1) ²⁺/PAA solution with a final[Cd_(0.9) ²⁺Mg_(0.1) ²⁺] of 1.25 mM and final PAA concentration of 0.67mg/mL.

Example 31 Polyanion Collapse with Cd²⁺—Zn²⁺(90%) Cations

In a 400 mL plastic beaker, 400.0 mg of PAA (Sigma, Average M_(V) 1.2million) was dissolved in 200 mL deionized water. The plastic beaker wasimmersed in a hot water bath (approximately 80-90° C.) and was stirredvigorously for at least 30 minutes or until all of the solid PAA haddissolved. Once the solution had cooled to room temperature, the pH wasadjusted to 6.8 using 0.1 M NaOH. pH measurements were done usingnarrow-range pH paper. 10 mL of a Cd_(0.1)Zn_(0.9)(NO₃)₂ solution wasprepared by mixing together of 1 mL and 9 mL of 5 mM Cd(NO₃)₂ and 5 mMZn(NO₃)₂ solutions, respectively. The total concentration of metal ionsin solution was 5 mM. 10 mL of pH-adjusted PAA was obtained and placedin a 50 mL beaker followed by the dropwise addition of 10 mL of themetal salt solution under vigorous stirring to yield 20 mL of a Cd_(0.1)²⁺Zn_(0.9) ²⁺/PAA solution with a final [Cd_(0.1) ²⁺Zn_(0.9) ²⁺] of 2.5mM and final PAA concentration of 1 mg/mL.

Example 32 Polyanion Collapse with Cd²⁺—Zn²⁺(10%) Cations

In a 400 mL plastic beaker, 400.0 mg of PAA (Sigma, Average M_(V) 1.2million) was dissolved in 200 mL deionized water. The plastic beaker wasimmersed in a hot water bath (approximately 80-90° C.) and was stirredvigorously for at least 30 minutes or until all of the solid PAA haddissolved. Once the solution had cooled to room temperature, the pH wasadjusted to 6.8 using 0.1 M NaOH. pH measurements were done usingnarrow-range pH paper. 6 mL of a Cd_(0.9)Zn_(0.1)(NO₃)₂ solution wasprepared by mixing together of 5.4 mL and 0.6 mL of 5 mM Cd(NO₃)₂ and 5mM Zn(NO₃)₂ solutions, respectively. The total concentration of metalions in solution was 5 mM. 10 mL of pH-adjusted PAA and 4 mL ofdeionized water were obtained and placed in a 50 mL beaker. 6 mL of themetal salt solution was then added dropwise under vigorous stirring toyield 20 mL of a Cd_(0.9) ²⁺Zn_(0.1) ²⁺/PAA solution with a final[Cd_(0.9) ²⁺Zn_(0.1) ²⁺] of 1.5 mM and final PAA concentration of 1mg/mL.

Example 33 Polyanion Collapse with Cd²/Mn²⁺(1%) Cations

In a 400 mL plastic beaker, 400.0 mg of PAA (Sigma, Average M_(V) 1.2million) was dissolved in 200 mL deionized water. The plastic beaker wasimmersed in a hot water bath (approximately 80-90° C.) and was stirredvigorously for at least 30 minutes or until all of the solid PAA haddissolved. Once the solution had cooled to room temperature, the pH wasadjusted to 6.8 using 0.1 M NaOH. pH measurements were done usingnarrow-range pH paper. 25 mL of a Cd_(0.99)Mn_(0.01)(NO₃)₂ solution wasprepared by mixing together of 24.75 mL and 0.25 mL of 5 mM Cd(NO₃)₂ and5 mM Mn(NO₃)₂ solutions, respectively. The total concentration of metalions in solution was 5 mM. 20 mL of the pH-adjusted PAA and 25 mL ofdeionized water were obtained and placed in a 100 mL beaker. 15 mL ofthe metal solution was then added dropwise under vigorous stirring toyield 60 mL of a Cd_(0.99) ²⁺Mn_(0.01) ²⁺/PAA solution with a final[Cd_(0.99) ²⁺Mn_(0.01) ²⁺] of 1.25 mM and final PAA concentration of0.67 mg/mL.

Example 34 Polyanion Collapse with Cd²⁺/Hg²⁺(50%) Cations

In a 400 mL plastic beaker, 400.0 mg of PAA (Sigma, Average M_(V) 1.2million) was dissolved in 200 mL deionized water. The plastic beaker wasimmersed in a hot water bath (approximately 80-90° C.) and was stirredvigorously for at least 30 minutes or until all of the solid PAA haddissolved. Once the solution had cooled to room temperature, the pH wasadjusted to 6.8 using 0.1 M NaOH. pH measurements were done usingnarrow-range pH paper. 25 mL of a Cd_(0.5)Hg_(0.5)(NO3)2 solution wasprepared by mixing together of 12.5 mL and 12.5 mL of 5 mM Cd(NO₃)₂ and5 mM Hg(NO₃)₂ solutions, respectively. The total concentration of metalions in solution was 5 mM. 20 mL of the pH-adjusted PAA and 25 mL ofdeionized water were obtained and placed in a 100 mL beaker. 15 mL ofthe metal solution was then added dropwise under vigorous stirring toyield 60 mL of a Cd_(0.5) ²⁺Hg_(0.5) ²⁺/PAA solution with a final[Cd_(0.5) ²⁺Hg_(0.5) ²⁺] of 1.25 mM and final PAA concentration of 0.67mg/mL.

Example 35 Polyacrylic Acid Crosslinking with 4 G25T8 Germicidal Lamps

60 mL of Cd_(x) ²⁺Pb_(1-x) ²⁺/PAA was prepared according to Example 29and was placed in a 150.0 mL glass beaker. The solution was exposed to 4G25T8 germicidal UV lamps (approximate power is 12 μW/mm²) forapproximately 30 minutes under vigorous stirring. The irradiatedsolution was then dialyzed against deionized water for 3 hours, changingthe deionized water reservoir every hour. Collapsed PAA withCd_(x)Zn_(1-x)(NO₃)₂, Cd_(x)Mn_(1-x)(NO₃)₂, Cd_(x)Mg_(1-x)(NO₃)₂ . . .was UV-irradiated in a similar manner for approximately 1 hour. Theviscosity of the collapsed irradiated, dialyzed solutions was much lowerthan that of collapsed, un-irradiated solutions. These solutions werefilterable using a 0.2 μm nylon syringe filter.

Example 36 Cd_(0.5)Pb_(0.5)Te/PAA Nanoparticles

Under ambient conditions, 20 ml of Cd_(x) ²⁺Pb_(1-x) ²⁺/PAA producedaccording to Example 35 was placed in a 100 mL round bottom flask. ThepH was adjusted to 11 using 1.1 M NaOH. pH measurements were done usingnarrow-range pH paper. To this solution, 20.4 mg of NaBH₄ and 28.3 mg oftrisodium citrate were added while the solution was being stirred.Immediately after the addition of the borohydride and the citrate, 0.625mL of 0.01 Na₂TeO₃ was added. The solution develops a yellow colour uponaddition of the tellurium-containing salt. The solution was thenrefluxed for approximately one hour under N₂ atmosphere to allowCdPbTe/PAA nanoparticles to form. The absorbance and emission spectra ofthe resulting solution after one hour of reflux is shown in FIG. 23.Unfortunately, the colloidal solutions were extremely unstable uponexposure to air and this was marked by a quick disappearance of thecharacteristic absorbance and emission spectra shown in FIG. 23.

Example 37 Cd_(0.9)Zn_(0.1)Te/PAA Nanoparticles

Under ambient conditions, 8 mL of Cd_(0.9) ²⁺Zn_(0.1) ²⁺/PAA producedaccording to Example 32 was placed in a 25 mL round bottom flask, andcross-linked using the permitted lamp as hereinabove described. To thissolution, 15 mg of NaBH₄ and 30 mg of trisodium citrate were added whilethe solution was being stirred. Immediately after the addition of theborohydride and the citrate, 0.3 mL of 0.01 Na₂TeO₃ was added. Thesolution develops a peach colour upon addition of thetellurium-containing salt. The solution was then refluxed forapproximately two hours to allow CdZnTe/PAA nanoparticles to form. Theabsorbance and emission spectra of the resulting solution after twohours of reflux are shown in FIG. 24.

Example 38 Cd_(0.99)Mn_(0.01)Te/PAA Nanoparticles

Under ambient conditions, 10 mL of Cd_(0.99) ²⁺Mn_(0.01) ²⁺/PAA producedaccording to Example 33 was placed in a 25 mL round bottom flask, andcross-linked using the permitted lamp as hereinabove described. To thissolution, 20 mg of NaBH₄ and 37 mg of trisodium citrate were added whilethe solution was being stirred. Immediately after the addition of theborohydride and the citrate, 0.313 mL of 0.01 Na₂TeO₃ was added. Thesolution develops a peach colour upon addition of thetellurium-containing salt. The solution was then refluxed forapproximately one hour to allow CdMnTe/PAA nanoparticles to form. Theabsorbance and emission spectra of the resulting solution after one hourof reflux are shown in FIG. 25.

Example 39 Cd_(0.5)Hg_(0.5)Te/PAA Nanoparticles

Under ambient conditions, 10 mL of Cd_(0.5) ²⁺Hg_(0.5) ²⁺/PAA producedaccording to Example 34 was placed in a 25 mL round bottom flask, andcross-linked using the permitted lamp as hereinabove described. To thissolution, 16 mg of NaBH₄ and 29 mg of trisodium citrate were added whilethe solution was being stirred. Immediately after the addition of theborohydride and the citrate, 0.313 mL of 0.01 Na₂TeO₃ was added. Thesolution remained colourless upon addition of the tellurium-containingsalt. The solution was then refluxed for approximately one hour to allowCdHgTe/PAA nanoparticles to form. However, the refluxed solution was notfluorescent.

Example 40 Formation of Methylene Blue/PAA Nanoparticles

In a 400 ml plastic beaker, 400.0 mg of PAA (Sigma, Average M_(V) 1.2million) was dissolved in 200 ml deionized water. The plastic beaker wasimmersed in a hot water bath (approximately 80-90° C.) and was stirredvigorously for at least 30 minutes or until all of the solid PAA hasdissolved. Once the solution has cooled to room temperature, the pH wasadjusted to 6.8 using 0.1 M NaOH. pH measurements were done using narrowrange pH paper. 20.0 ml of this PAA solution was placed in a glassbeaker and to this, 20.0 ml of aqueous 5.0 mM Methylene Blue solutionwas added dropwise under vigorous stirring. After all of the MethyleneBlue solution was added, the viscosity of the mixture was observed to bemuch less than the original PAA solution. The resulting solution wasexposed to UV radiation using 4 G25T8 germicidal UV lamps for 1.5 hours.The viscosity of the UV-irradiated Methylene Blue/PAA solution was lessthan the viscosity of the solution not exposed to UV radiation.

Example 41 Silver Nanoclusters

A PAA-PSS solution of was prepared as follows: 25.0 ml of 2 mg/ml PAA(1.2 million MW, pH adjusted to 6.8 with NaOH) was prepared and placedin a glass beaker. To this, 2.5 mg of PSS (70K MW) was added and thesolution was stirred vigorously on a magnetic stirplate for about 20minutes. The resulting solution, 25.0 ml PAA-PSS was clear and viscousand had a pH of about 6.8.

PAA-PSS was collapsed with Ag⁺ in the following manner. Ag⁺ collapsingsolution was prepared by diluting 2.0 ml of 0.10 M AgNO3 to 25 ml withdeionized water. This was then added dropwise to 25 ml of PAA-PSS undervigorous stirring. The rate of addition of the Ag+ collapsing solutionwas approximately 4-5 ml/min.

Once all of the collapsing solution has been added, the solution wasthen exposed to UV radiation under a UV-germicidal lamp forapproximately 4 hours to obtain Ag⁺/PAA-PSS. A spectra of this resultingsolution is shown in FIG. 26. This solution can easily be filteredthrough a 0.2 micron syringe filter.

The silver was reduced as follows to produce silver nanoclusters: to theresulting solution after crosslinking, an excess of NaBH4 was added(approximately 5.0 mg solid NaBH4 for 25.0 ml of Ag⁺/PAA-PSS) while thesolution was being stirred. The solution turned from blue to amber-brownafter borohydride addition. The spectra of the solution (now Ag/PAA-PSS)is shown below in FIG. 27.

We believe, without being held to theory, that this process producessilver nanoclusters, clusters of less than about 100 silver atoms, asdemonstrated by the shift in the surface plasmon UV-Vis peak.

Example 42 Doped Nanoclusters: Indium-Tin/PAA

Sn(II) and In(III) precursor solutions can be prepared as follows. 32 mMSnCl₂ can be made by dissolving 0.2443 g of SnCl₂ in 39 ml of deionizedwater and 1 ml of 1M HCl. 24 mM In(NO₃)₃ can be made by dissolving0.2488 g of In(NO₃)₃ in 40.0 ml deionized water. A 4 mM (In—Sn)precursor solution (1:1 mole ratio In(III):Sn(II)) can be made by mixing4.2 ml of 24 mM In(NO₃)₃ and 3.1 ml of 32 mM SnCl₂ and diluting themixture to 50 ml with deionized water.

In(III)-Sn(II)/PAA can be made by adding 25 ml of a 4 mM (In—Sn)precursor solution dropwise to 25 ml of pH 6.8 2 mg/mL PAA undervigorous stirring. Once all of the precursor solution has been added,the resulting mixture is exposed to a UV germicidal lamp forapproximately 2 hours or until the solution could be filtered through a0.2 micron syringe filter.

The mixed In—Sn oxide nanoparticle can be formed by adding NaOH to 20 mlof the UV exposed solution until the pH was between 10-11 and heatedunder reflux for 2 hours. Confirmation of the chemical structure can beobtained using XRD.

Example 43 Doped Nanoparticles and Nanoclusters: Zinc-Sulfur/PAA-PSS₅%

A ZnS nanocluster was prepared as follows. 200.0 ml of Zn²⁺/PAA-PSS₅%(prepared substantially according to Example 9) was placed in a 250 mlround bottom flask. To this, 8.0 mL of 0.10 M aqueous Thioacetamidesolution was added. The resulting mixture was stirred and heated to80-90° C. for 17 hours under reflux. After heating, the solution wasclear and had a very light yellow color. The UV-visible absorptionspectrum of the sample diluted 10× is shown in FIG. 28.

Example 44 Doped Nanoparticles and Nanoclusters: Zn/Cd

A 40/60 mole ratio Zn/Cd-PAA solution (Solution 1) was made as follows.2.4 ml of 5 mM Zn(NO₃)₂ and 3.6 ml of 5 mM Cd(NO₃)₂ were mixed togetherand diluted to 10 ml with deionized water. This solution was addeddropwise, under vigorous stirring to 10 ml of pH 6.8, 2 mg/ml PAA (1.2million MW). The final solution was exposed to a UV germicidal lamp for2 hours. A 90/10 mole ratio Zn/Cd-PAA solution (Solution 2) was made asfollows. 9.0 ml of 5 mM Zn(NO₃)₂ and 1.0 ml of 5 mM Cd(NO₃)₂ were mixedtogether. This solution was added dropwise, under vigorous stirring to10 ml of pH 6.8, 2 mg/ml PAA (1.2 million MW). The final solution wasexposed to a UV germicidal lamp for 2 hours. (Zn—Cd)S/PAA was made fromSolutions 1 and 2 by adding 0.5 ml of 4.5 mM Na₂S to 0.5 ml of Solutions1 and 2. The resulting emission spectra of the formed (Zn—Cd)S/PAAnanoparticles for a 40/60 mole ratio of Zn/Cd-PAA solution (2902) and a90/10 mole ratio of Zn/Cd-PAA solution (2904) are shown in FIG. 29.

Example 45 Biopolymer Particles: Chitosan

In various embodiments, the polymer portion comprises a biomolecule,e.g., a protein or other polymer. A nanoparticle using a randomcopolymer, here the biomolecule chitosan, was formed as follows. 0.9974g Chitosan (High molecular weight, SIGMA) was dissolved in 100 ml 1%acetic acid solution. The initial pH of the solution right afterdissolution is about 3.8-4.1 using pH paper. For pH-viscositymeasurements, the pH of the initial Chitosan solution was adjustedbetween the pH range 1-6 to determine different viscosities at differentpH. Chitosan starts to precipitate above pH 7; pH was adjusted using 0.5M HCl or 0.5 M NaOH. Viscosity was measured in terms of “Efflux times(s)”—the time it took the solution level to move between 2 points in anostwald viscometer. pH vs “Efflux time” plots are shown in FIG. 30.

Collapse of chitosan with a salt (NaCl) was also performed. To measurethe amount of salt required to collapse chitosan, different solutionswith varying NaCl concentrations were prepared and their correspondingsolution viscosities were measured. For viscosity measurements, 20 ml of2.5 mg/ml Chitosan solutions with different NaCl concentrations weremade (0, 1, 4, 8, 12, 16, 32 mM NaCl). For example, to prepare 20.0 mlof 2.5 mg/ml chitosan with 4 mM NaCl, 10 ml of 5 mg/ml Chitosan wasplaced in small beaker. To this, 10 ml of 8 mM NaCl was added dropwiseunder vigorous stirring. The resulting mixture's viscosity was measuredusing an ostwald viscometer. The point of collapse was taken as whenthere was a change of slope in the efflux time vs NaCl concentrationplot, at about 5 mM NaCl in FIG. 31.

Example 46 Zn Nanoparticle Formed by Vapor-Based Reduction

A composite nanoparticle can be formed as follows. 300 mL of Zn²⁺/PAAprepared substantially as described in Example 5 using Zn(NO₃)₂ as thecollapsing agent can be crosslinked according to Example 12. The solventis then removed using rotary evaporation and the resulting powder placedin a crucible. The crucible is placed in a reducing atmospherecontaining H₂ until Zn/PAA nanoparticles are formed. Existence of the Znnanoparticles can be confirmed using electron microscopy.

Example 47 Collapse by pH

The polymer portion can be collapsed by a variety of approaches. Invarious embodiments, to a polyelectrolyte in its extended conformationis added a counterion—in an amount an insufficient to collapse thepolymer. The counterion will associate with the polyelectrolyte but notcollapse it. A collapse transition can be then driven, e.g., by one ormore of: changing pH, solvent change, evaporation of solvent,cavitation, etc., to form a nanoparticle.

In various embodiments, collapse is facilitated and/or inititiated by achange in pH as follows. To a 50 mL solution of PAA (2 mg/mL) add 30 mLof ddH₂O in one portion followed by 12 mL of Cd(NO₃)₂ solution (5 mM)dropwise. After completion of addition the solution, adjust pH to about3.5 by adding a solution of HNO₃ (5 mM). The resulting solution can beirradiated with UV light (254 nm) for 1 h. The resulting solution havinga much decreased viscosity relative to uncollapsed PAA.

Example 48 Catalytic Activity of Nanoparticles

The present example illustrates the catalytic activity of variousembodiments of nanoparticles of the present inventions in performing aHeck reaction. A schematic for the reaction is shown in FIG. 32.

The nanoparticles were prepared as follows. In a round-bottom flask wereput iodobenzene (22 uL, 0.20 mMol, 1 equiv.), tertbutyl acrylate (34.4uL, 0.24 mMol, 1.2 equiv), K₂CO₃ (69 mg), ddH2O, palladium nanoparticlesprepared according to the present invention, (100 uL, ˜1.67 mM inpalladium, 0.1%), and additive (Bu₄NCl (56 mg) if indicated). Initially0.5 mL ddH2O was added, then 0.5 mL more was added after two days toprevent the reaction from drying up. The mixture was stirred at refluxat about 100° C. for 7 days, allowed to cool down to room temperature,and extracted with CH₂Cl₂. The combined extracts was dried with MgSO₄,filtered, and evaporated in vacuo. The NMR of the crude product wastaken to confirm the success of the coupling reaction.

Example 49 Isotopic Substitutions

In various embodiments, isotopically substitutes nanoparticles can beformed. For example, isotopically enriched CdTe—ZnS/PAA compositenanoparticles can be produced according to a slightly modified versionof Example 17. Instead of 167 μL of 39.5 mM Na₂S in its standardisotopic state, 167 uL of 39.5 mM Na₂ ³⁵S was used, where ³⁵S denotesthe isotope of sulphur having a mass of about 34.9690322 amu, which canbe obtained from commercial sources.

Example 50 Pyrolysis of Nanoparticles

ZnO nanoparticles were prepared as follows: 200 ml Zn²⁺/PAA was placedin a 3 necked round bottom flask. A condenser was placed on the centerneck and the other 2 necks were covered with rubber septa. NaOHsolution. For 200 ml Zn²⁺/PAA 50 mL of 13.4 mM NaOH was needed. 100 mlof 13.4 mM NaOH was prepared by adding 134 μL of 10 N NaOH to 50 mLwater in a 100 mL graduated cylinder. The solution was diluted to 100 mlwith DI water. Next, the round bottom flask with the Zn²⁺/PAA was heatedto about 80 degrees. 50 ml of the 13.4 mM NaOH was added with a syringepump (using a needle) at a rate of 5 ml/min under vigorous stirring.Once all of the NaOH was added (50 ml), the solution was stirred at 8degrees for 30 mins. Next, it was allowed to cool and was placed in arotavap until the solution was reduced to about 10 ml. It was thenprecipitated and allowed to dry; the dried precipitate was flesh-creamin color. When re-suspended the solution is clear. The UV-Vis absorptionspectrum of the resulting solution is shown in FIG. 33.

In various embodiments, the material can be sintered. For example,0.1762 g of the dried precipitate from above was placed in a ceramiccrucible was heated in a furnace under ambient atmosphere. Thetemperature was ramped up from room temperature to 450° C. at a rate of10° /sec and was kept at 450° C. for 2 hours. After furnace treatment,the ppt was colored grey-white and the final weight was 0.0698 g. Someof the grey-white powder was dispersed in water. The spectra of theresulting suspension is shown in FIG. 34. TEM images of the particlesafter heating to 450° C. are also shown in FIG. 35. Samples were alsoheated to about 550° C. and about 700° C. for the same amount of time.The resulting powder from 550° C. heat treatment had a lighter greycolor compared to the powder obtained from 450° C. heat treatment.Heating the dried precipitate to 700° C. produced powders that weregrey-white in color. Spectra of the different heat treated powdersuspensions in water had UV-visible spectra similar to the one shown inFIG. 33. This pyrolysis/sintering process can lead to changes in thenanoparticle size as shown, it is believed without being held to theory,by the spectral shift of the UV-Vis absorption peak and by the TEMimages.

Example 51 Carbide Nanoparticles

In various embodiments, carbide nanoparticles can be formed as follows.Collapsed, crosslinked V³⁺/PAA is formed substantially according toexample 12, using VCl₃ as a precursor. The resulting product is heatedin a furnace to 1200 K for 6-12 hours. This can be done, e.g., under (1)low pressure, e.g., vacuum conditions, and/or (2) a reducing atmosphere.In various embodiments, the heating is done under a vacuum of less thanabout 1×10⁻⁴torr. Confirmation of the production of vanadium carbidenanoparticles can be obtained using x-ray diffraction.

Example 52 Dispersability of Nanoparticles

In various embodiments, nanoparticle dispersability can be increased asfollows. For example for CdTe/PAA, CdTe/PAA nanoparticles are producedas described in Example 12 or 16. After synthesis, the approximateconcentration of PAA in solution is maintained at about 1 mg/ml. Thenanoparticles are precipitated out of solution and then dried. The driednanoparticles can be resuspended in less water than the originalsolution making up a more concentrated solution of nanoparticles. Invarious embodiments, up to about 32 times the original concentration.This can bring the effective 1.2 million MW PAA concentration to about32 mg/ml. This exceeds the normal solubility of PAA in water.

Example 53 Removal of Polymer from Composite Nanoparticle by Cleavage

The polymer portion can be removed by a variety of approaches, such as ,e.g., cleavage of encapsulating crosslinks and/or destruction of theencapsulating crosslinks, and/or cleavage of a coblock and/or chemicalcleavage of backbone chains, etc.

For example, in various embodiments polymer can be removed as follows.Under ambient conditions, place 500 mL of CdTe/PAA produced according toExample 16 in a flat-bottom vessel. Place this vessel under a 4 G25T8germicidal UV lamps (approximate power is 12 μW/mm²) for approximately12-18 hours (or until the polymer is removed, as measured byagglomeration tendency and/or changes in optical properties). Dialyzethe irradiated solution against deionized water for 3 hours, changingthe deionized water reservoir every hour. When imaged by electronmicroscopy, isolated and aggregated nanoparticles can be observed butsubstantially no encapsulating polymer film is observed.

Example 54 Nanoparticle Formed by Decomposition of a Complex

In a plastic 400.0 mL beaker, dilute 3.0 mL of poly(diallyldimethylammonium chloride) (PDDA) [Sigma, Average M_(W)400-500K, 20 wt % in water] to 300 mL with deionized water. Stir thesolution stirred for 10 minutes. Obtain 5.0 mL aliquots and place in 20mL scintillation vials. To each dropwise add with vigorous stirring 5.0mL of aqueous potassium ferrocyanide solutions (2 mM-20 mM) to yieldabout 10 mL of [Fe(CN)₆]⁴⁻/PDDA solutions with different [[Fe(CN)₆]⁴⁻]between 1 and 10 mM and a final PDDA concentration of about 1 mg/mL. Therelative viscosity of each solution can be measured with an Ostwaldviscometer. The point at which the viscosity as a function of[Fe(CN)₆]⁴⁻ concentration changes suddenly can be taken as the PDDAcollapse point with [Fe(CN)₆]⁴⁻, such that at lower concentrations thePDDA is primarily in an extended conformation. The [Fe(CN)₆]⁴⁻/PDDA canbe exposed to 4 G25T8 germicidal UV lamps (approximate UV power is 12μW/mm²) for 1 hour under vigorous stirring to provide crosslinking. Theresulting product is refluxed and production of iron or iron oxidenanoparticles can be confirmed by electron microscopy.

All literature and similar material cited in this application,including, patents, patent applications, articles, books, treatises,dissertations and web pages, regardless of the format of such literatureand similar materials, are expressly incorporated by reference in theirentirety. In the event that one or more of the incorporated literatureand similar materials differs from or contradicts this application,including defined terms, term usage, described techniques, or the like,this application controls.

The section headings used herein are for organizational purposes onlyand are not to be construed as limiting the subject matter described inany way.

While the present inventions have been described in conjunction withvarious embodiments and examples, it is not intended that the presentinventions be limited to such embodiments or examples. On the contrary,the present inventions encompass various alternatives, modifications,and equivalents, as will be appreciated by those of skill in the art.Accordingly, the descriptions, methods and diagrams of should not beread as limited to the described order of elements unless stated to thateffect.

Although this disclosure has described and illustrated certain preferredembodiments of the invention, it is to be understood that the inventionis not restricted to those particular embodiments. Rather, the inventionincludes all embodiments which are functional or mechanical equivalenceof the specific embodiments and features that have been described andillustrated.

The claims should not be read as limited to the described order orelements unless stated to that effect. It should be understood thatvarious changes in form and detail may be made without departing fromthe scope of the appended claims. Therefore, all embodiments that comewithin the scope and spirit of the following claims and equivalentsthereto are claimed.

1. A method for producing a composite nanoparticle, comprising the stepsof: changing the conformation of a dissolved polyelectrolyte polymerfrom a first extended conformation to a more compact conformation bychanging a solution condition so that at least a portion of thepolyelectrolyte polymer is associated with a precursor moiety to form acomposite precursor moiety with a mean diameter in the range betweenabout 1 nm and about 100 nm; and cross-linking the polyelectrolytepolymer of the composite precursor moiety to form a compositenanoparticle.
 2. The method of claim 4 wherein the precursor moiety hasa diameter in the range between about 1 nm and about 50 nm.
 3. Themethod of claim 1, wherein the composite nanoparticle has a diameter inthe range of about 1 nm to about 100 nm.
 4. The method of claim 1,wherein the composite nanoparticle has a diameter in the range of about1 nm to about 50 nm.
 5. The method of claim 1, wherein the cross-linkingis performed by exposing the polyelectrolyte polymer to ultravioletradiation.
 6. The method of claim 1, wherein the precursory moiety isadded to the polyelectrolyte polymer solution to cause the change insolution condition.
 7. The method of claim 1, wherein the change insolution condition is a change in pH.
 8. The method of claim 1, whereinthe change in solution condition is a change in temperature.
 9. Themethod of claim 1, wherein the change in solution condition is a changein ion concentration.
 10. The method of claim 1, wherein the change insolution condition is a change in the solubility of the polyelectrolytein the solvent.
 11. The method of claim 1, wherein a collapsing agent isadded to the polyelectrolyte polymer solution to cause the change insolution condition.
 12. The method of claim 1, wherein a second solventis added to the polyelectrolyte polymer solution to cause the change insolution condition.
 13. The method of claim 11, wherein the collapsingagent comprises at least one ionic species.
 14. The method of claim 13,wherein the ionic species comprises one or more inorganic salts, organicsalts, or combination thereof.
 15. The method of claim 1, wherein theprecursor moiety is selected from the group consisting of a chargedorganic ion, an inorganic salt, a metal-containing compound, an alloycontaining at least one metal and an elemental metal.
 16. The method ofclaim 1, wherein the polyelectrolyte polymer is a copolymer.
 17. Themethod of claim 1, wherein the precursor moiety is confined by thepolyelectrolyte polymer.